On the one hand, the rebuke could be seen as a purely political decision devoid of any real ethical basis. On the other, anti-semitism is very real, very dangerous, and alive and kicking in the US (see Charlottesville), and politicians need to be super careful and qualified in how they approach things so as not to encourage it.

You can be sure though the Dems won't rebuke Netanyahu for saying this:

https://www.theguardian.com/world/2019/mar/10/benjamin-netanyahu-says-israel-is-not-a-state-of-all-its-citizens

State-institutionalised racism is apparently OK if it's your friends who do it.

I know Kamala Harris and Warren have also come out in support for her. But the Democrats looked absolutely awful as they through Ilhan Omar under the bus because bad faith actors decided to pound the table and accuse Omar of baseless anti-semitism.

Meanwhile as Baden pointed out, Netanyahu said the quiet part out-loud, i.e. he views Israel as an monolithic ethnic-state. There is a very real conversation that needs to occur in American regarding out relationship to Israel, and the more Zionists (which mostly refers to Evangelist Christians, rather than American Jews, by the way) attempt to silence this debate and accuse detractors of anti-semitism (even if those detractors are Jewish!) the worse it will be for them in the future.

Israel has learned basically that peace with Palestinians isn't a priority as:

a) Similar wars with it's neighbours, like the Yom Kippur war, cannot happen anymore and Israel is totally dominant in every field of conventional warfare.
b) Even if Assad does manage to end the civil war, the country poses no threat to Israel (especially after it's nuclear weapons program was destroyed by Israel).
c) The time-to-time fighting with the Palestinians (and Hezbollah) can be contained and limited that it doesn't represent any kind of problem to the government or Israel in general
d) The current state doesn't represent an economic problem to Israel: the economy is doing just fine. There are no international sanctions that would force Israel to think otherwise.
e) Israel has already approach states like Saudi-Arabia as everything isn't viewed through the prism of the Palestinian question anymore.

Above all, the US has become an extremely untrustworthy ally which just fumbles up in the Middle East. It has lost it's influence severely in the Middle East and it's Middle East policy, if you can think there is one, is simply a train wreck. Just look at Iraq and the poor Kurdish allies of the US in Syria. Hence if one would assume that a 'Bernie/Warren'-administration or similar would change US policy towards Israel and cut for example aid to this wealthy country, it wouldn't be a huge crisis for Israel. Israel has good relations with Russia and Turkey and basically the change would create a bigger storm in the US political scene than in Israel.

@Baden @Maw
+1
Thank you both for your thoughtful responses. In this world wired together tighter than a drum, when the Middle East sneezes, the rest of us catch cold. Anti-Semitism is, like other forms of racism and intolerance, a blight upon humanity. We must strive to reduce it, if not completely eliminate it. But like the fable of the boy who cried wolf, false accusations of such for narrow political purposes undermine the real problem and cloud the issue.

The Jewish people have had an undeniably difficult history. May those in Israel live peacefully and happily. Any criticism (from myself and others of like mind) of the current government is with the intent to help ensure and increase that peace and happiness. For all, without exception.