$100 PLO8 on stars. 3rd hand at the table, I'm on the button with a full stack. EP has $25, SB has $75.

On the aforementioned button, I get [Ac][7s][2c]. Few limpers, I raise pot to $6. SB and EP both call. (Side question: if a shortstack commits 25% of his stack preflop by calling a raise like that, what should I put them on?)

Flop: [8h][3c]. Good enough. The shortstack bets $5 into the pot. I have no clue what that means, but I'm always ready to lose a stack, so I raise pot. SB calls to my surprise, and shortstack calls allin.

Turn: . SB instantly moves in, I call.

River: .

Outcome: I scooped here: SB has A433, SB had 4556, with the flush draw to the hearts....

Obviously I got very lucky for high. On the flop, should I be reckoning to play for low only or even for a quarter? How do I play this flop if EP has more money behind? Can you come up with any defense for SB's play?