But there was help for people like this uncle. There were massive campaigns to address vaccine misinformation and conspiracy theories about COVID, to which they collectively said "No thanks, I did my own research." What were we supposed to do, set up reeducation camps and forcibly round them up and ship them off? I can't really see that being a viable solution.

There was help. Still is. These people have agency and the same access to information you and I do. If anyone believes something in spite of the available information it's because they want to. They're just dumb, but this kinda dumb kills other people too, not just themselves.