50NL flop set of 5's, not best turn or river and now he open shoves

[Lego05]

Villian is 22.18/8.41/.85(mostly due to pre-flop) over 523 hands.
He's gone to showdown 30% out of 125 and won 57% out of 37.

Same villian from this hand that happened about 30 minutes earlier (Villian had 64 in this hand):
http://forumserver.twoplustwo.com/showflat.php?Cat=0&Number=10163474&an=&page=&vc=1
What do you do here?

PokerStars No-Limit Hold'em, $0.50 BB (6 handed) Hand History Converter Tool (http://poker-tools.flopturnriver.com/Hand-Converter.php) from FlopTurnRiver.com (http://www.flopturnriver.com) (Format: 2+2 Forums)

CO ($50)
Button ($39.20)
SB ($52.20)
BB ($228.05)
UTG ($57.80)
Hero ($54.25)

Preflop: Hero is MP with 5/images/graemlins/heart.gif, 5/images/graemlins/diamond.gif.
<font color="#666666">1 fold</font>, <font color="#CC3333">Hero raises to $2</font>, <font color="#666666">2 folds</font>, SB calls $1.75, <font color="#666666">1 fold</font>.

Flop: ($4.50) 8/images/graemlins/club.gif, 5/images/graemlins/spade.gif, 7/images/graemlins/diamond.gif <font color="#0000FF">(2 players)</font>
SB checks, <font color="#CC3333">Hero bets $3.5</font>, SB calls $3.50.

Turn: ($11.50) 3/images/graemlins/heart.gif <font color="#0000FF">(2 players)</font>
SB checks, <font color="#CC3333">Hero bets $8.5</font>, SB calls $8.50.

River: ($28.50) 6/images/graemlins/spade.gif <font color="#0000FF">(2 players)</font>
<font color="#CC3333">SB bets $38.2 (All-In)</font>, Hero ???

[HasPair]

Seems like you're beat here. He probably had 99/some other straight. I think you have to fold this.

[ocdscale]

Easy fold I think.
His hand seems like a clear draw, and you've been betting all the way.

[Skleice]

His stats worry me. He's not the type to call preflop with 69 or 64 out of position. But I think he would raise preflop or on the flop with an overpair. I would not be surprised to find he has 77 or 88 with a higher set. Even then, I'm surprised he wouldn't raise to beef up the pot and protect against that board.

[Genz]

I don't think he has a made straight on the flop. 99 or 9T are more likely. You basically only beat an over- or twopair. Well, I beat a 2pair once that open-shoved the river like this. Since there is 6578 on the board, I tend to believe that this is a value-bet.