When you say that science is never "Established", that's horse pockey. Established means we have a high level of confidence (not absolute). Yes, things get updated, for example we now don't go around saying that "stress causes ulcers". And when it comes to vaccines, multiple high quality studies have failed to find a relationship between vaccines and autism, while the original work has been discredited (shown to be false) and retracted. Yet the news cycle about that caused large numbers of people in the US to not get their kids vaccinated for many different things (and also blame the vaccines for their children's autism). (to be realistic, vaccines do have side effects and there is an entire program detected to detecting those problems).
As for whether he's been a public health official: no, but he has worked on environmental and public health problems before (I don't recall if this is before or after he ate so much fish he got mercury poisoning).
I don't think many people are complaining about him speaking against processed food, but again, the policy he promotes should be thoughtful, not knee-jerk.