And immediate censorship is (in my opinion) counterproductive.
I'm pro-vaccine in general, and I won't deny that in the slightest. But I'd much rather have a (neurotypical -- children who should not be vaccinated for other reasons are of course exempted from this discussion) child getting some vaccines than none, and I'd rather have children vaccinated on a delayed schedule than not at all.
When boards shut down thoughtful discussion, it tends to send people to extremely polemic sites for information. They naturally are more prone to search for sites which present the viewpoint they already support, and many of these sites will only present information that supports their view, whilst denigrating any other possible viewpoints (this goes for sites on both sides of the debate -- I've seen some ridiculous hyperbole on pro-vaccine sites as well). It tends to shut people down rather than helping them to think, and it also makes it look like they have something to hide.