I suspect the location of the post makes a difference. If, for example, it was posted on the wall of an anti-censorship group that is decidedly opposed to the

I suspect the location of the post makes a difference. If, for example, it was posted on the wall of an anti-censorship group that is decidedly opposed to the actions of the Chinese government, then posting "freedom" there could quite easily be seen as expressing support for the group and therefore "disharmony". Probably it wasn't quite as clear-cut as that (such an overtly anti-censorship group would probably be inaccessible on the Chinese Facebook anyway), but the context probably had something to do with it; I'd be curious to hear what it was. But it's a pretty bad sign when, seeing someone use the word "freedom", your immediate reaction is suspicion, trying to decide whether or not it shows that the speaker is an enemy. And that's how it must be for the Chinese internet police who make decisions like this one.