I don't see the problem. Facebook is not a government entity, and thus is not required by anyone at all to not censor.
If the statement that you are making is that Facebook is hypocritical in that on the one hand they operate under a mantra of openness and on the other hand they censor, then sure, that's a problem; however, hypocrisy is a global problem that in some way is applicable to every human and every company.
Facebook has very little legal obligation, but that doesn't mean we shouldn't be upset and to talk about it as much as possible.
Facebook could also randomly delete pictures and emails if it liked and it may be within their legal right to do so, but I'd find it odd if you just said, "If they legally can do it, I won't complain".
If the statement that you are making is that Facebook is hypocritical in that on the one hand they operate under a mantra of openness and on the other hand they censor, then sure, that's a problem; however, hypocrisy is a global problem that in some way is applicable to every human and every company.