You’d have to ask them. If your family or the families of people in your community were being slaughtered by the incumbent administration, you might discover you have a red line after all. Fortunately for you, you’ll probably never really know.

As so many Harris-voting lemmitors have instructed me, stopping the genocide is not on the effective ballot as-presented, so no, they are not assisting continuing what is absolutely a genocide. The goal is that they either pressure Harris to not be a ghoul, because they presume she cares about winning more than aiding genocide (this is most likely false) or, if Harris sticks to her guns and either loses or wins by such slim margins that it makes the Dem winning next election without stopping Israel much more hazardous, they (the Muslim/Arab voters) can extract concessions, because even electoral politics doesn't end with one election cycle, and some strategies aimed at maximizing some long term result can introduce a risk or even a guarantee of short-term costs.

I don't believe, like I think those voters do, that Dems would trade Israel slaughtering with impunity even for a guaranteed victory, but I think them demonstrating that unwillingness has its own value, since the DNC needs to be brought down. I don't expect you to agree to this and am not terribly interested in persuading you, I'm just offering an explanation.

The knee jerk response from lefties is that any insult or criticism of people who are members of a minority is racist, regardless of if it has anything to do with race (or race adjacent).