Party Poker No-Limit Hold'em, $ BB (10 handed) FTR converter on zerodivide.cx

BB ($13.43)
UTG ($57.25)
UTG+1 ($15)
UTG+2 ($16.60)
MP1 ($29.60)
Hero ($50)
MP3 ($39)
CO ($93)
Button ($41.38)
SB ($38.75)

Preflop: Hero is MP2 with Q, 3. Hero posts a blind of $0.50. SB posts a blind of $0.25.
UTG calls $0.50, 1 fold, UTG+2 calls $0.50, 1 fold, Hero (poster) checks, 2 folds, Button calls $0.50, SB (poster) completes, BB checks.

Flop: ($3) J, 3, 3 (6 players)
SB checks, BB checks, UTG checks, UTG+2 checks, Hero checks, Button bets $4, SB folds, BB folds, UTG folds, UTG+2 folds, Hero calls $4.

Turn: ($11) 6 (2 players)
Hero checks, Button bets $4, Hero calls $4.

River: ($19) 5 (2 players)
Hero checks, Button bets $20.03, Hero raises to $40.06, Button folds.

Final Pot: $79.09

Results in white below:
Hero has Qh 3d (three of a kind, threes).
Outcome: Hero wins $79.09.

I am posting this hand because it is of interest to me. Is it +EV to for villain to fold like this when hes got 4/5 of his stack in the middle, even if he's almost he's losing?

I definitely admire his discipline to lay down a hand like that, not feeling pot committed at all, whether its +EV or not.