If I understand Julio Cabrera correctly, you are describing a similar argument. He thinks that this world is morally disqualifying precisely because it entails that we be moral monsters. There's no way around it.. If we want to get our "projects accomplished", it becomes part of it.. whether destroying other life, manipulation, or frustrating each other's preferences and in order to justify it.

Cabrera believes that in ethics, including affirmative ethics, there is one overarching concept which he calls the "Minimal Ethical Articulation", "MEA" (previously translated into English as "Fundamental Ethical Articulation" and "FEA"): the consideration of other people's interests, not manipulating them and not harming them. Procreation for him is an obvious violation of MEA – someone is manipulated and placed in a harmful situation as a result of that action. In his view, values included in the MEA are widely accepted by affirmative ethics, they are even their basics, and if approached radically, they should lead to the refusal of procreation.

For Cabrera, the worst thing in human life and by extension in procreation is what he calls "moral impediment": the structural impossibility of acting in the world without harming or manipulating someone at some given moment. This impediment does not occur because of an intrinsic "evil" of human nature, but because of the structural situation in which the human being has always been. In this situation, we are cornered by various kinds of pain, space for action is limited, and different interests often conflict with each other. We do not have to have bad intentions to treat others with disregard; we are compelled to do so in order to survive, pursue our projects, and escape from suffering. Cabrera also draws attention to the fact that life is associated with the constant risk of one experiencing strong physical pain, which is common in human life, for example as a result of a serious illness, and maintains that the mere existence of such possibility impedes us morally, as well as that because of it, we can at any time lose, as a result of its occurrence, the possibility of a dignified, moral functioning even to a minimal extent. — Wiki on Antinatalism

Perhaps, although that quote - and I am not sure if it accurately reflects his actual views - implies that all he is saying is that we cannot help but live harmful lives.
But that's not yet a moral monster. What makes someone a moral monster is that they are morally entitled to live an injustice wreaking life.

Of course, there are limits and we are obliged to do 'something' to ameliorate injustices (and parents are obliged to do a great deal - they ought to sacrifice their comforts). But not much. For the most part, we do no wrong in living comfortable lives of great destruction. Which is terrible.

When you say "injustices", you are talking about the usual ones brought up like environmental degradation, harm to poorer people, especially in second/third world countries, and harm to animals, right?

Yes.

People will say that this is more a matter of policy, and can change to some degree and is measurable, so can be evaluated. In other words, they might say that it is not intrinsic but simply the state of current affairs due to bad practice. Even if they agreed to the premise that there must be some injustice, they would say this can be minimized to some (or large) extent, if we changed our ways.

They may be right (although they really aren't - we can't change much), but changing them would be costly to us - it would require we make sacrifices. And we have no obligation to make those sacrifices. We do no wrong continuing as we are. That's what makes us moral monsters. We are doing no wrong in leading these lifestyles. Parents are - they ought not lead them. But we - we who have not created the problem for which the sacrifices would be needed - are not obliged to make the sacrifices.

An objection to my moral monster argument is that it undermines the antinatalism I am using it to support. For many, it would seem, want to have children and to live the lifestyle that having them involves (that is, they enjoy changing dirty underwear and sleepless nights and sex-less relationships and having no money and being tiny tyrants and so on). So, for them securing a happy life for themselves involves having children. And although that creates an injustice, they're nevertheless permitted to create such an injustice. Their moral monsterdom extends to procreation itself.

Note: that's a good criticism. This: "you antinatalists are miserable misanthropes and you want us all to die and blah di blah di blah" is not.

In response: first, even if the criticism goes through, the moral monster argument would still establish something like antinatalism (and that may still qualify as antinatalism, depending on how you use the term). For it would still show that refraining from procreation is a good thing to do, it's just that it is beyond the call of duty. That is, refraining from procreation would be a supererogatory thing to do.
Second - and again, even if the argument goes through - the point would only apply to those for whom it really is true that procreation is needed for them to secure a happy life. The fact is that procreating is one of those activities that people have been taught to think will make them happy, but that seems highly unlikely to. It is, in this respect, analogous to thinking that taking up heroin is a good recipe for a happy life. For some, perhaps. But for most - including most who are convinced it is - it is not. There's what will actually make you happy, and there's what you believe will do so, and although the two are often the same, they are sometimes not. Most people procreate without having given it much thought and they do so in ignorance of what it is likely to do to them. So, 'in fact' it may be only a minority for whom procreation is needed to secure happiness. That so many 'think' it will make them happy just reflects the widespread stupidity that infects the bulk of humanity.
Third, the criticism to some extent addresses a straw man, as the claim is not that we are entitled to do anything whatever in order to try and secure for ourselves the happy lives we deserve. The point is that there are limits to what can be demanded of us - we who are not responsible for our situation, that is - in terms of preventing injustices from befalling others. The fact the world is a very unjust place and the fact our own actions are partly responsible for this does, I think, give rise to us having an obligation to do 'something' to ameliorate them. We're not total moral monsters, then. We're not wholly excused from considering to what extent our actions contribute to the injustices of the world. We're not wholly excused from making sacrifices, especially not those that it is very easy for us to make. Refraining from procreating is very plausibly a sacrifice it is very easy to make and that would make a very big difference in terms of how much injustice it would prevent. By contrast giving up meat, say, is harder and makes scant difference in real terms. So in terms of the sacrifice/benefit ratio, refraining from procreating is very plausibly something we are obliged to do, even though we are moral monsters.

Creating someone also creates kind and ethical people like you who care about others and want to make the world a better place. Bestowing benefits cannot be disregarded in favour of a single-minded focus on impositions. Clearly, the world has a lot of problems. Yet, there is also a lot of good that deserves to exist.

deserve to die — Bartricks

Only the worst, the most diabolical, of criminals deserve to die! Draw your own conclusions about abortion/antinatalism.

Morality is built around 2 concepts:

1. Algos (sorrow/joy)

2. Thanatos (death/life)

Pro-choicers may get themselves off the hook by saying the fetus feels no pain (1) when being aborted but they're still killing life and hence abortion is unethical (2).