Even in a scenario where nobody took the “he’s better than Trump approach,” I think it would have still been too late.
Any hesitation in taking a stance against genocide is going to look like a begrudging concession. I agree that the optics are even worse now that it has gone on for half a year without any significant change, but he cemented the public perception of himself by the end of the first week of continued support after we were all made aware of Israel’s actions. Changing his mind at any point after that looks like a politician doing what a slimy politician does: chasing public opinion to stay in power.
Granted, it might have worked to convince some people. But, I believe there’s enough of an overlap between that demographic and the “any blue will do” voters that the only ones left would have permanently rejected the idea of voting for him the moment they felt he supported genocide. That is to say, I think the only people left not choosing him over Trump are either disenfranchised voters or hardline moralists who don’t realize what’s at stake by letting Trump win.