ESR was not banned for having the wrong opinion – many others expressed similar opinions both before and after his messages. But ESR, over the course of a few days where he returned to the mailing list, was increasingly unable to express those opinions in a professional manner.

While the moderators never stated their rationale, an unfortunate combination of off-list and on-list replies leaked one of ESR's blocked emails[1] although there were possibly others. Given the context of the discussion, ESR is not only deeply unprofessional here, but also making personal attacks against Coraline Ada Ehmke. Disagreement is OK, attacks are not.

And as Gil notes in that email, how ESR is promoting his cause is actually hurting and undermining open source, not rescuing it. I'd add that such attacks are even more unacceptable when they come from an ex-President or Cofounder.

If I had been the moderator to make that call, I'd even have considered banning ESR without any particular evidence. That guy isn't new to the scene but has a long history of troublesome behavior. Even his first message upon return did not provide anything new to the discussion, so there was no reason to believe that keeping him around would provide any value to anyone. When his messages were largely brushed off (because they contributed no novel points aside from BeInG wRiTtEn By ThE cOfOuNdEr) that only seemed to encourage him to get more extreme, thus running straight into a ban. If not after that message, surely after the next.

[1]: http://lists.opensource.org/pipermail/license-discuss_lists....