KQs against a 9/6 tighty

I think his 9VPIP / 6 PFR range beats my 20/10 range; therefore I conclude that he has one of 2 hands: AA, AK, less likely KK. Problem is that I don't get the river bet, which is the questionable laydown by me. I guess, on this kind of board, which has a bunch of draws to it, I would expect him to check / check the river. Is he really going for value with a pot sized bet on the river?

Full Tilt No-Limit Hold'em, $0.10 BB (9 handed) - Full-Tilt Converter Tool from http://www.flopturnriver.com

Button ($3.68)
SB ($13.33)
BB ($2.18)
UTG ($10.03)
UTG+1 ($12.79)
MP1 ($1.75)
MP2 ($10.04)
Hero (MP3) ($11.31)
CO ($9.15)

Preflop: Hero is MP3 with Ks, Qs
UTG bets $0.40, 3 folds, Hero calls $0.40, 4 folds

Flop: ($0.95) 3s, Kh, 9h (2 players)
UTG bets $0.70, Hero calls $0.70

Turn: ($2.35) 6s (2 players)
UTG bets $1.90, Hero calls $1.90
From the amount of pressure he's shown, what can I really expect here? He's got one of 3 hands: AA, KK, or AK - all of which beat me. I call because of my spade draw, and spade draw alone.

River: ($6.15) 3c (2 players)
UTG bets $4.80, Hero folds

Total pot: $6.15 | Rake: $0.41

Results:
UTG didn't show
Outcome: UTG won $5.74

So is an ultra tight player betting near pot on the river? Is this a river value bet? I am fairly certain I am beat by the river and therefore lay down, licking my ~$3 wounds from this little expedition.