NL200: Good spot to block?

[Claunchy]

Villain is unknown, but he doesn't have a full staack, and he limped UTG, so let's assume he sucks.

PokerStars No-Limit Hold'em, $2 BB (6 handed) internettexasholdem.com

SB ($198)
Hero ($338.15)
UTG ($116)
MP ($422.10)
CO ($351)
Button ($200.70)

Preflop: Hero is BB with Q[img]/images/graemlins/diamond.gif[/img], K[img]/images/graemlins/diamond.gif[/img].
UTG calls $2, <font color="#666666">2 folds</font>, Button calls $2, <font color="#666666">1 fold</font>, Hero checks.

Flop: ($7) 8[img]/images/graemlins/club.gif[/img], T[img]/images/graemlins/spade.gif[/img], Q[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(3 players)</font>
<font color="#CC3333">Hero bets $6</font>, UTG calls $6, Button calls $6.

Turn: ($25) 2[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(3 players)</font>
<font color="#CC3333">Hero bets $18</font>, UTG calls $18, Button folds.

River: ($61) 9[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(2 players)</font>
Hero checks, <font color="#CC3333">UTG bets $50</font>, Hero folds.

Final Pot: $111
I raise preflop here often but not always, and I've been really active lately so I decided not to beef up the pot OOP.

This a good river to throw out a $20 block, or is c/f fine?