I mean, don’t they have a right to say if not “A because of B” but “B happened right after A”, which could be an observation? At what point we should do thought police? I do agree it sounds not very well educated but that could be a good start to get this education from someone in the comments. If it’s only echo chamber of like-minded people, I doubt thought policing helps in this situation as well and nothing will change their minds at this moment. If anything, blocking people’s posts strengthen conspiracy theorist ideas about invisible forces controlling information.
If the post literally reads "MY DAUGHTER HAS AUTISM BECAUSE OF [X] VACCINE" then it's not that hard to refute with scientific literate.
What is much harder to police with a coherent set of guidelines is a facebook page where thousands of moms have each written "I got my child vaccinated and then they developed autism". When a new mom, with little sleep and little background in biological science, who is still on the fence about vaccines, see those thousand posts all together it paints a compelling narrative without ever really having contradicted science.
I mean, that's misinformation. When you know that no medical literature supports the idea that autism is caused by vaccine, and you still spread it...