I did not say that the Arab world is united against Israel. However, there is significant anti-Israeli public sentiment everywhere in the Arab world, even more so than against Iran. Even if Arab leaders are not as sensitive to public sentiment as more democratic countries, they can't easily ignore it entirely, and becoming the main supporter of Israel is not a comfortable domestic position for any Arab leader.
Also, you are grossly misrepresenting public opinion in the USA and the EU. In the USA there is a significant and extremely vocal minority, especially among the Democratic party base, that deeply care for the genocide in Gaza. This has been visible in the major student protests, and in the significant protest votes in Democratic primaries (>10% undecided in some states!). And given the extremely tight election, this is very likely to cause issues for Biden. Now, whether reversing support for the genocide would cause larger issues is debatable, but I think unlikely - as most of the avid Israel-can-do-no-wrong supporters are not going to vote against Trump anyway.
In Europe the situation is even more difficult for the pro-genocide camp, as the population, especially in Western Europe, and doubly especially among the significant Arab, Pakistani, Indian, Turkish, and North African immigrants, is much more sensitive to the issue of colonial genocide.
The student protests, which are for obvious reasons not representative of the whole population, are themselves numerically a small portion of the faculty and staff at the institutions they're taking place at. Excellent recent examples of this: repeated instances of walkouts or sit/stand protests at commencement ceremonies, where everyone involved is arranged out on a field, almost as if to make these kinds of tallies easy to make (but serious tallies of protests at Columbia, Chicago, and UCLA have also been made). It just doesn't take a lot of people to make a lot of noise.
The "10% undecided" thing is a statistical null result, mirroring the last Democratic reelection campaign (Obama's, against Romney), which didn't include any attempted organized effort to lodge protest votes with "undecided" and still ran up those counts.
Polling --- Pew is a good place to start --- shows Israel below every other "major" issue, even among 18-29 year olds --- except (ironically) student debt. The issue gets less important as you go up in age brackets into cohorts that actually turn out and vote.
The groundswell of support for Palestine in America is, I believe, largely an Internet phenomenon. It's easy to forget that we're the weird people who tune in to this stuff. Most people just live their lives, and, for reasons that are straightforward to understand, care a lot more that a 12 pack of Diet Coke got weirdly expensive than about whatever is happening across the world. We have the same problem marshaling support for Ukraine!
Also, you are grossly misrepresenting public opinion in the USA and the EU. In the USA there is a significant and extremely vocal minority, especially among the Democratic party base, that deeply care for the genocide in Gaza. This has been visible in the major student protests, and in the significant protest votes in Democratic primaries (>10% undecided in some states!). And given the extremely tight election, this is very likely to cause issues for Biden. Now, whether reversing support for the genocide would cause larger issues is debatable, but I think unlikely - as most of the avid Israel-can-do-no-wrong supporters are not going to vote against Trump anyway.
In Europe the situation is even more difficult for the pro-genocide camp, as the population, especially in Western Europe, and doubly especially among the significant Arab, Pakistani, Indian, Turkish, and North African immigrants, is much more sensitive to the issue of colonial genocide.