As someone who has only recently become aware of rfk in any form other than people referring to him as a kook, I'm surprised by statements like these.
Maybe his positions in the past were more extreme? This is from a town hall tonight, I'm curious if this is the kind of complete nonsense that you mean:
https://m.youtube.com/watch?v=KLxBwIupF88
The highlights seem to be that he and his kids are vaccinated, but that he wants to see childhood vaccines subjected to placebo controlled trials (and he claims with some substantiation that the existing ones have not had placebo controlled trials, though I can't validate that).
I don't know, it didn't seem all that whacky to me.