What temporary measures did you take? Did you only remove the posts or did
you ban the offending user? In the latter case, prepare to receive death
threats in your mailbox. Like I did...
That is the problem with moderation. The moderators suffer all the bad
consequences. In particular, accusations of censorship (although it is not
censorship: the Trisquel community is entitled to its own rules and anyone
can publish whatever she wants on her own server).
The current +1/-1 system has the advantage of delegating the moderation to
the community as a whole. I would be in favor of only making the system a
little bit more strict: a problematic user who received more -1 than +1 could
have her posts hidden as soon as someone click the -1 button. As far as I
remember a chat with quidam (months ago), the current can be configured in
this way. No additional implementation work is needed.
Banning is ineffective because a new account can be created. For instance
chaosesqueteam has another account under the name vPro. With the
reinforcement policy I suggest, the new account has his first offensive posts
hidden as soon as somebody click the -1 button because the account is not
associated with any +1 post.