I heard this idea ...that, 'meaninglessness is meaningless’ and, in being so, that therefore it could not in principle be.

That is, I heard the idea that for some reason inherent to the nature of reality, the notion of ultimate nihilism is simply illogical and therefore – purely as an amoral consequence - that the question of our own ultimate fate, happily, needs must have a constructive answer. - Or again, the idea that though our ultimate fate be not ordained by a 'Devine Will' and is necessarily in accord solely with, 'The Nature of Things', that nonetheless this, 'Nature' must intrinsically be ultimately constructive. - Phew!

Even so, it would, I suppose, be to somewhat miss the point – were this argument ever to prove valid – to regard such an eventuality as being a version of serendipity! :)

NB: - Btw: 'In the Nature of Things' - Was it Virgil, ''De Rearum Natura' or something like that, meaning 'On the Nature of Things'?...Don't suppose anyone on this site is ever likely to enlighten me?