AF = 8 means precisely what? Over how many hands? That he bets or raises 8 times as often as he calls. That doesn't mean he raises every c-bet, it just means he folds OR raises them, never calls.

If you are going to go by AF alone, then you should always re-raise here, because he never calls! Of couse, this is ridiculous - but it's the same error that says you should call just becuse he raises alot.

I'm not saying folding is clearly better - but it's not horrible either.