Is this river play stoooooopid?

[Buccaneer]

I was quiting for a break and did not get the auto post for the blinds unchecked quick enough. I looked at my hand and my plan was to get away from it at the first opportunity and go get breakfast. The flop hit and all those pretty diamonds hit. Nice looking ones, high ones but with out the A. I am now drawing to a straight, flush or straight flush, I bet out and get only calls, no raises.

The turn makes my flush (there may be others out there) but I can still improve. My bet is not raised so I think that there may be another weaker flush out there but not the A or T. We loose the last straggler and it is HU to the river and the 8 diamond hits. So the board does not play but my 9 does. There are 6 diamonds out only 2 that can hurt me. There has been no agression but mine on this hand so he can not have the A or T so I bet out hoping he has trips or a straight and he calls. SB had played only a few hands and I was begining to label him as passive.

Party Poker 0.50/1 Hold'em (7 handed) converter

Preflop: Hero is BB with 9[img]/images/graemlins/diamond.gif[/img], 4[img]/images/graemlins/heart.gif[/img].
UTG calls, <font color="#666666">1 fold</font>, MP2 calls, <font color="#666666">2 folds</font>, SB completes, Hero checks.

Flop: (4 SB) K[img]/images/graemlins/diamond.gif[/img], Q[img]/images/graemlins/diamond.gif[/img], J[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(4 players)</font>
SB checks, <font color="#CC3333">Hero bets</font>, UTG calls, MP2 folds, SB calls.

Turn: (3.50 BB) 3[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(3 players)</font>
SB checks, <font color="#CC3333">Hero bets</font>, UTG folds, SB calls.

River: (5.50 BB) 8[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(2 players)</font>
SB checks, <font color="#CC3333">Hero bets</font>, SB calls.

Final Pot: 7.50 BB

Addittional info in white but not results: <font color="white">My notes on this clown NOW say Passive, Passive, Passive! Will not bet or raise a flush. </font>

[nickg1532]

No, I would bet the river too

He did nothing but check and call all the way through, I would figure him for having a low diamond at best, or perhaps no diamonds at all and just one or two pairs. There are only 2 cards that can beat you, of course you're going to bet the river.