Anything other than siding with Israel would lead to claims of anti-semitism and criticism from the very powerful Isreal lobby, not to mention Republicans.
I’m not sure of that actually.
By far not all American Jews are Israel supporters in this case.
Not all Republicans as well.
There needs to be some way to raise their voice for those who are heavily against what’s happening, which will give such a turn lots of supporters.
And, of course, I hope you do understand that people yelling about anti-semitism in this case are different from people yelling about “white genocide” in only one aspect - they are defending mass murder happening right now, while the latter are just relatively harmless racists.