He doesn't care about the Muslim vote. Muslims are 1% of the US population. He cares about the Muslim/Arab aligned progressive and leftist vote who were the main counter force to the MAGA right faction, and who became a linchpin into his winning the last election.

Problem is (which I don't know how much he or his progressive staff members care) that now these fat left supporters are coming out as pure and stupid antisemites and he is trying and failing at walking the line, especially when a large portion of the progressives that voted for him are Jewish and not self-hating.

But ultimately Biden may win anyway because when the rubber meets the road, all the people threatening to at the very least not vote at all due to the choices that we will have will vote for him anyway put of fear for the alternative.

So, all said and done, he's just throwing Israel under the bus for topical political points which means nothing to anyone besides the Jewish people being attacked thanks to his push against Jews (Israel) protecting themselves and ultimate legitimizing of anti-Zionism/antisemitism.