They are doing this to protect Israel, and protecting Israel has nothing to do with antisemitism. Because Zionism and Judaism are pretty much unrelated!
Israel is strategically advantageous for the US and the rest of the West. Having a Western strong arm in the middle east is the goal geopolitically. Nobody actually cares about Jews or really thinks they're entitled to that land. We just really, really want that land because of course we do.
I don't think the rest of the west besides the USA is all that interested in the strategic value of Israel; I'm not even sure the USA is strategically interested… well, not economically and militarily at least, I think the politicians care about the country for the sake of their own re-election.
If the US only cared about power-projection in that area, Cyprus would also be an easy option (like the UK does with https://en.wikipedia.org/wiki/Akrotiri_and_Dhekelia), as would Turkey (a NATO member), and these days they could probably have an easy time working with Egypt.
Sure, Israel has a lot of stuff going for it (nukes that won't necessarily be blamed on the USA; MOSAD is infamous; etc.), but counting on them alone is an all-eggs-in-one-basket strategy that comes with risks.
US expends a lot more effort propping Israel up than it gains from Israel's existence. Our politicians often talk about how important it is to have "an ally in the region", but if you look at that proposition closely, it falls apart because the cost of this particular ally is basically making everyone else there into an enemy.
Israel is strategically advantageous for the US and the rest of the West. Having a Western strong arm in the middle east is the goal geopolitically. Nobody actually cares about Jews or really thinks they're entitled to that land. We just really, really want that land because of course we do.