Lets be real here, if someone calls your region shit you will be mad.
a fun ( not fair ) punishment should really be round bonus for the opposing team, giving the next team they play against a 3 round bonus so the game starts with 3-0
Trash talk is part of the fun! It adds to the tension.
But, obviously more people will support and follow teams which show good sportsmanship. I think being hated due to your public persona is punishment enough. For example, I dislike most of Sentinels (obviously except Tenz because he is a true gentleman), and therefore really enjoy it everytime they loose... which has been 3 out of the last 5 games... and they are apperently the best in NA...