The government silencing stupid people is wrong and dangerous. A group of like minded individuals speaking up and persuading a private company to put limits on acceptable behavior is a great thing. There would be no cover up of the ignorance. This is a confrontation and a rejection of this specific ignorance
I have no problem with a private company deciding it doesn't want to host a particular piece of speech. It's their resources and their prerogative. But I joyfully defend a private company's decision _not_ to silence the legal free speech its visitors enjoy, and I praise Facebook's recognition that gagging someone really doesn't confront their ignorance. The way to confront ignorance is to provide information, not to remove it.
I also rebuke the idea that I should petition anyone to limit my "acceptable speech" (speech is the only behavior possible on the internet) beyond legal demands. Anyone old enough to sign Facebook's Terms & Conditions is also old enough to know exactly how to reject speech they aren't interested in confronting: stop reading and look elsewhere.
I agree with the sentiment of your post title, but as concerns a petition to silence those propagating this reprehensible opinion, I also agree with something a Facebook employee said:
"Silencing stupid people is not how you make stupid people go away. It's by pointing out how stupid they are and bringing those people into the light of day so everyone with a shred of common sense can see who they are and remember never to give them an ounce of respect in any aspect of life. You do not combat ignorance by trying to cover up that ignorance exists. You confront it head on. Facebook will do the world no good by trying to become its thought police." http://www.facebook.com/note.php?note_id=83400756950
I'm with Falterer, here. The person on my friends list that "liked" this particular page eventually "unliked" it after the general outrage it caused among her friends. She was simply too embarrassed to share this opinion publicly. I think that's a much better outcome than simply silencing her.