He dared management to ban him; and they should take him at his word.

Management is wise to the triple dog dare tactic. :-)

... prevent the consideration mechanism being used to control his output

His output does not meet the criteria for reapage. I will personally unreap any post of his (or anyone else's) which gets reaped solely for reasons of technical content.

the only option left is the current downvoting and attachment of warnings.

Properly, those are the first and best options.