Strange river check raise

[Absolution]

MP is the same spazzy (35/25/4) LAG from my other hand. I have notes on the SB:

Raised 69o in the SB when folded to and then waited for the turn with a flopped 2 pair.
Bet folded a mid flop after raising pre-flop.
Peeled an A high flop and then folded the turn in an unraised pot.
Bets fearlessly with A high.
Waited for the turn with just top pair.

He's 50/18/1.5. He likes to bet draws and can overplay in spots. He likes to slowplay.

PokerStars 0.50/1.00 Hold'em (5 handed) Poker Stars Converter Tool from FlopTurnRiver.com (Format: 2+2 Forums)

Preflop: Hero is BB with 7[img]/images/graemlins/heart.gif[/img], 6[img]/images/graemlins/spade.gif[/img].
<font color="#666666">1 fold</font>, <font color="#CC3333">MP raises</font>, Button calls, SB calls, Hero calls.

Flop: (8 SB) 5[img]/images/graemlins/spade.gif[/img], 2[img]/images/graemlins/heart.gif[/img], 7[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(4 players)</font>
SB checks, <font color="#CC3333">Hero bets</font>, <font color="#CC3333">MP raises</font>, Button folds, SB calls, Hero calls.

Turn: (7 BB) K[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(3 players)</font>
SB checks, Hero checks, MP checks.

River: (7 BB) 5[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(3 players)</font>
SB checks, <font color="#CC3333">Hero bets</font>, MP folds, <font color="#CC3333">SB raises</font>, Hero folds.

Final Pot: 9 BB