Just to make clear once again: he was blocked for posting the list of editors on the other website.
Thank you! It was by no means clear to me before now that this was the fundamental reason.
The relevant part of the blocking policy is this: http://en.wikipedia.org/wiki/Wikipedia:Blocking_policy#Personal_attacks_whic...
The full text follows:
"Blocks may be imposed in instances where threats have been made or actions performed (including actions outside the Wikipedia site) which expose other Wikipedia editors to political, religious or other persecution by government, their employer or any others. In such a case a ban for a period of time may be applied immediately by any sysop upon discovery. Sysops applying such sanctions should confidentially notify the members of the Arbitration Committee and Jimbo Wales of what they have done and why. See No personal attacks.
This provision is rarely used."
Even if we accept that this provision applies in this case (I do not, but I would agree that it is a borderline case) the provision calls for a "ban for a period of time", not an indefinite block.
Regards, Haukur