ummmmmmmm, there are several possible strategies with barring. One says that you ban the person for life, another says that you only bar when behaviour becomes unacceptable. It looks to me as though the AB is more of the latter - what do you think ?
I know of another site (ho ho) where if they get the slightest whiff as to who you are you get a 25-year ban.
A point I made on another now-deleted thread, is that if a previously barred user returns, they'll want people to know that it is them returned, I would have thought anyway. Why come back if you intend to stifle your personality ?
In some cases though, even a small change of heart should ensure survival.
But I am no man's keeper.