3bet pot - monotone board - facing donk

50plo - clubgg - min 35 vpip

limp/3bsqueeze to get HU vs shortstack
There's literally no side pot in the middle so villain is never bluffing right????
But he's only repping nuts? But he didn't bet or check/raise the turn
His line makes 0 sense to me yet he's never "bluffing"????

Hero (UTG+1): 153.64 BB
MP: 479.9 BB (VPIP: 46.67, PFR: 26.67, 3Bet Preflop: 25.00, Hands: 19)
CO: 140.14 BB (VPIP: 20.00, PFR: 13.33, 3Bet Preflop: 0.00, Hands: 19)
BTN: 32.26 BB (VPIP: 50.00, PFR: 0.00, 3Bet Preflop: 0.00, Hands: 2)
SB: 140.24 BB (VPIP: 33.33, PFR: 0.00, 3Bet Preflop: 0.00, Hands: 19)
BB: 234.8 BB (VPIP: 60.00, PFR: 12.00, 3Bet Preflop: 0.00, Hands: 32)
UTG: 75.96 BB (VPIP: 46.15, PFR: 15.38, 3Bet Preflop: 0.00, Hands: 16)

SB posts SB 0.5 BB, BB posts BB 1 BB

Pre Flop: (pot: 1.5 BB) Hero has K♦ K♥ 9♠ 7♥

fold, Hero calls 1 BB, MP calls 1 BB, fold, BTN raises to 5.5 BB, fold, BB calls 4.5 BB, Hero raises to 23.5 BB, fold, BTN calls 18 BB, BB calls 18 BB

Flop: (72 BB, 3 players) 8♠ J♠ T♠
BB checks, Hero checks, BTN checks

Turn: (72 BB, 3 players) 5♣
BB checks, Hero bets 15 BB, BTN calls 8.76 BB and is all-in, BB calls 15 BB

River: (110.76 BB, 3 players) Q♥
BB bets 55.38 BB, fold