give this guy a hand

[PokerBob]

canterbury 15/30 9 handed
button here is a regular at canterbury. i think he is a pro; a semi-pro at the very least. He cold-calls many raises preflop. i have not been in the game very long, so i don't have a read on the initial raiser.

some dude opens in MP, I fold in the hijack, CO makes it 3-bets (this guy is an idiot. he tries all kinds of fancy plays postflop. seems to get a kick out of getting people to fold better hands, but he is clearly a losing player. he also likes to do retarded aggressive stuff preflop, but i have never seen him 3-bet pf with pure trash) button cold-calls 3bets. what can button have here that his cold-call of 3 bets makes sense?