Flop action on 4bet pot

Hi,

Vilain is 32/32/17 on 56 hands.

How would you interpret that vilain donk on the flop? Considering preflop action, i basically exclude AA-KK-QQ that would have shipped pre. On baby board like this, OOP and without the initiative, i don't see vilain betting 99-TT for value or protection.

Based on this, I elected to push flop. What do you think of the thought process, is it excessive?

Thanks

PokerStars - $0.05 NL (6 max) - Holdem - 6 players
Hand converted by PokerTracker 4

MP: 188.2 BB
CO: 115.4 BB
Hero (BTN): 131.8 BB
SB: 90.8 BB
BB: 104.4 BB
UTG: 210.4 BB

SB posts SB 0.4 BB, BB posts BB 1 BB

Pre Flop: (pot: 1.4 BB) Hero has A♥ K♣

fold, fold, fold, Hero raises to 2.4 BB, fold, BB raises to 10 BB, Hero raises to 25 BB, BB calls 15 BB

Flop: (50.4 BB, 2 players) 5♠ 9♥ T♣
BB bets 25.2 BB, Hero ??