Villain isn't a reg and he's clearly not a good player (stats ~30/8), but I didn't have any reads. I thought that I would call if he bets the river. Is it better to bet/fold?

No-Limit Hold'em, $0.50 BB (6 handed) - Hold'em Manager Converter Tool from FlopTurnRiver.com
Hero (BB) ($102.90)
UTG ($50.75)
MP ($83.95)
CO ($60.25)
Button ($64.20)
SB ($21.65)

Preflop: Hero is BB with A, K
1 fold, MP calls $0.50, 2 folds, SB calls $0.25, Hero bets $2, MP calls $2, SB calls $2

Flop: ($7.50) 5, K, 9 (3 players)
SB checks, Hero bets $6, MP raises $12, 1 fold, Hero calls $6

Turn: ($31.50) 7 (2 players)
Hero checks, MP checks

River: ($31.50) 5 (2 players)
Hero checks