I mean, I don't honestly know what to tell you if you really don't think praising a communist dictator is a bad faith attack and that no one will care about it. Hillary actually brought his praise up of Castro in 2016, and that's one of the many reasons he lost Florida. if you praise Castro, you are not winning the state of Florida. We can handwave that away as "We don't have to win Florida" or whatever, but when Bernie is already having problems with older voters, when we know what the lines of attack are going to be, doubling down on shit like that is asinine. There are very few (if any) statements in politics that are entirely positive or entirely negative. Praising the troops is probably as close to universally positive as you can get, tbh. There is no benefit whatsoever to giving the benefit of the doubt to Fidel Castro. None whatsoever. There is no voter who is suddenly going to be "You know what, he's right. That Fidel....he had a damn good literacy program."
Like I said, it's just unforced error and kinda reinforces one of my biggest fears about him, that he won't revise past stances even if he feels he is 100% right. Pivot off this shit ASAP. We lose elections through a million tiny cuts targeted at various slices of the electorate. For you and I, this isn't a big deal. We're intelligent enough (or at least you are, I stand by the fact I'm a dumbass) to parse what he's saying. If a candidate wants to win Florida, you literally cannot get within 10 miles of a nice comment about Castro. There is, unfortunately, a pretty decent segment of the population who is still terrified of the Red Scare and this kind of shit leans hard into their priors about socialism.
I'm not hating on anyone who this doesn't bother, because I'm right there with you...it's just we know what the American Electorate is like. We know what they'll do, and pretending they'll somehow be different just because it's Bernie at the top of the ticket....
Honestly, I'm more upset about him not knowing how much his stupid M4A that's never going to happen is supposed to cost.