Look, man...
I have nothing against you as a mod, but I don't like seeing moderators using their powers in the wrong acts...
If you see him deserving a ban, then ban him but don't get yourself in childish acts like changing his signature because it won't bring anything good to the forum but a general viewing to the moderators here as people who abuse their powers to humilate others, and I think you don't want to look lke that...
Anyway, cheers...