I think they have a duty of care to their customers and should have taken action.
I believe they have a duty of care to take immediate action where there is a clear violation of the law.
Where there isn't, I don't see how they can be sheffif, judge and jury without defining lines in the sand that would obstruct fair comment, parody and unfavourable reviews of products and services by users as well until such time as a specific comment gets legally sanctions as within the boundries of the law.
On the basis of what you would like to see, the purveryor of fake holy magic water who turned my corner of rural Italy into picadilly fucking circus would have been able to silence my protest without first having to get a court to sanction it as over a legal boundary. He was already turning my life upside down. Having to let him carry on while I was censored into silence, with the removal of my one opportunity to open the lid on what was really going on and point out the unintended consequences of coachloads of pilgrims decending on us, is not a compromise I would feel comfortable accepting when there are other routes to punish lawbreakers without restricting my ability to make fair comment.
The legal line between proffering an opinion and slander/harrassment/ some other malicious endevour is best left to the forces of order and the judicary. Not facebook, who wpuld be more interested in arsecovering, and consequently set a fixed line so low that fair comment was censored too.
You had access to legal recourse when somebpdy stepped over the boundaries of the law. I would not have had the same had I been censored PRIOR to him being required to seek legal sanction before shutting me up.
And that drove the fucker mad.
A grassroots whispering campaign is one example. Irritating, strange and vindictive buggers pre internet found wierd and horrible ways to damage reputation and make wholly baseless claims.
The benefit of a medium like facebook is that from the very first instinct to be a git ....a papertrail is left.(which is why I was careful to stay eithin the limits of the law rather than waltz staight over it) Knuckles being rapped, or the thought that it could land them in hot water, due to good supporting evidence is far more likely to happen with modern coms than it was with the more cloaked "he said, she said" methods of yesteryear. I think eventually the penny will drop and those more inclined to be morally iffy will return to stratagies of old, but in the meantime those who scribble unfair, unwarrented, unsubstansiated, libelous bollocks all over facebook are a lot more vulnerable to a heavey hand on their shoulder or a costly civil case than those who go for off line and less obvious route.
I really don't want anymore censorship than we already have. DMV wotsitface is already being used by some bloggers to try and close down blogs that justofiably crisitse them. It is not within the spirit of the law at all. But placing a heavey onus on server space providers to react immediately at initial protest rather than risk prosecution has proved a useful tool in the hands of those who would prefer to spout crap and not have to deal with rebuttals.
I totally understand why you were unhappy with what happened and the sense of being powerless to stop it, but unintended consquences of legislation or regulation has to be considered as part of the landscape too.