WTF?

This is just a simple - WTF? I have no idea what the villain is doing!

Full Tilt Poker $0.25/$0.50 Pot Limit Hold'em - 8 players
The Official DeucesCracked.com Hand History Converter

BB: $84.20
UTG: $60.75
UTG+1: $50.00
MP1: $15.20
MP2: $30.00
CO: $53.00
BTN: $70.90
Hero (SB): $59.60

Pre Flop: ($0.75) Hero is SB with Ac Jd
1 fold, UTG+1 raises to $1.50, MP1 calls $1.50, 2 folds, BTN calls $1.50, Hero calls $1.25, 1 fold

Flop: ($6.50) Js 3d 8s (4 players)
Hero checks, UTG+1 checks, MP1 checks, BTN bets $3.25, Hero raises to $8.75, UTG+1 folds, MP1 folds, BTN calls $5.50
BTN is drawing to the spade.

Turn: ($24.00) 2h (2 players)
Hero bets $15.25, BTN calls $15.25
BTN continues to draw to the spade.

River: ($54.50) Jc (2 players)
Hero bets $34.10 all in, BTN calls $34.10
Does he really think a busted Ace high flush draw is good here? WTF? BUT HE WASN'T EVEN ON THE FLUSH DRAW!!! ALL HE HAS IS ACE HIGH!!!

Final Pot: $122.70
BTN mucks As 6d
Hero shows Ac Jd (three of a kind, Jacks)
Hero wins $119.70
(Rake: $3.00)