Anything that keeps the MSG rally in the news cycle the week before the election is good, even if it's for something stupid like this.
I mean, I think for a certain type of voter, they could look past the previous crap because it was about "other people" and he wasn't "talking about them" - he was talking about the "illegals," the "criminals", the "poor" etc., and maybe they even agreed with his viewpoints! Whereas part of the reason I think this particular insult is breaking through is because there are no restrictions to it - it's a short blatant insult to an entire island, no distinction by socioeconomic status - and it was captured in a few short seconds on video in front of a Trump/Vance sign, easily shared on social media.
It's a direct insult to many people's pride, and sometimes that's the kind of thing that cuts past all the noise of policy arguments, he said/she said, news analysis, etc. and just makes a whole bunch of people want to say "fuck you" in response.