Facebook currently enjoys essentially the same legal protection from liability arising from the content as do post and telephone companies (this is known as "common carriage"). The legal reasoning for such protection is that common carriers do not look into content of what they ship or transmit and merely provide a content-neutral service for the public.

This protection should not apply to the corporations which do exercise editorial control (or, as it happens, de-facto censorship) over the content they transmit, since they're no longer common carriers but rather publishers.

And, of course, the government is already heavily involved with Facebook - just not overtly but in the worst clandestine and unaccountable way imaginable. Anyone who thinks a company executive is going to deny anything spooks ask for is rather naive.