The first thing is that I did not "defend" by casting a spell. I did defend by autoassisting into combat. This is perfectly legal according to Trib rules.

Second, in response to Minyar, that warrant was issued with the blessings of the current Provost (i.e., the mortal responsible for interpretation), and I'm guessing the approval of the imms of the cabal. As a magistrate, that makes it no longer an interpretation, but an order.

You don't have to be sold, that's just how the laws are interpreted currently. You want to change that? Become Provost :)