He is an excellently designed card, in a low base attack, no DR clan. If he is so OP, then what would you recommend to balance him?
Bonnie is more OP. He doesn't need a ban. In my oppinion.
From what I saw last week on my way to the 10 credits, mono Piranas were quite a popular choice. Parmabarb has proven to be a very handy 2*, without which they're brought back a peg. It's quite normal for strong-but-(debatably) not-ban-worthy characters to be voted out just to reduce the frequency of that week's overplayed clans.
Parmabarb ban is justifiable; he is a very commonly used card and I could understand how he would be frustrating to play against. When he is banned I use Amiral Coco instead, who is very effective against any +/- attack clan