He got eight warnings in fewer than 2000 posts. After three widely spaced warnings in 2011 and 2012 (two for personal insults and one for ignoring mod instructions), he racked up the next three, all for personal insults, in two and a half months earlier this year:
http://boards.straightdope.com/sdmb/showthread.php?p=16455917#post16455917
http://boards.straightdope.com/sdmb/showthread.php?p=16460051#post16460051
http://boards.straightdope.com/sdmb/showthread.php?p=16709665#post16709665
At that point we suspended him for a month and told him he was on his last chance.
After his return, he got another warning for ignoring mod instructions (http://boards.straightdope.com/sdmb/showthread.php?p=16812018#post16812018) and then, yesterday, for personal insults (http://boards.straightdope.com/sdmb/showthread.php?p=16950326#post16950326).
Enough is enough.
twickster, for the SDMB