He's been "represented by the media, both mainstream and popular-alternative, as some kind of anti-vaxx leader" because he has gone on record multiple times questioning the efficacy of vaccines and advocating for people not to take them. Just because there are people even crazier than he is doesn't change the reality of his beliefs. Don't giga-brain your way into the wrong conclusion, occam's razor is right there.
But just for the readers at home who may want to buy this bs, here's RFK _on video_ with Lex Friedman, timestamped: https://www.youtube.com/watch?v=NPtBkw5uD-0&t=6938s
"There's no vaccine that is safe and effective", "the polio vaccine causes cancer". Says the man with brain worms.