Ugh, anti-vaccine conspiracy theorists. Why are there so many conspiracy theorists and alternative-science peddlers active in the US? We've got Young-Earth Creationists, homeopathy, tea party followers (to some extent), Obama birthers, 9/11 truthers, etc. etc.
Free speech is good and all that, and hearing alternatives to the public dogma is good, but only if they're based on intelligent arguments and proof instead of silliness.