If he's playing 30% of all hands while shortstacked, then he's not playing MSS. Also means that he's not going to be folding if you re-raise him.
I 4-bet him preflop, so he's all-in.
If MP2 still tags along after that, then he's going to have an all-in decision on that flop.
As played, I raise the flop. With the amount BB has behind, he's not folding anything, and I'd like to extract value from MP3, or get him out.
As played, I raise the turn to extract value from MP3.
As played, it looks like MP3 has a pocket pair 44-77. I'd bet the river. If MP3 had trips, he'd have raised the turn, and if he had a bigger pair, he'd have 3-bet preflop. You have nothing to fear from MP3. So extract from him to compensate for the times you don't beat BB.
Look at it this way: if his range is AQ+/JJ+, then you're only beaten by 12 combos of KK+, you chop with 1 combo of QQ, you beat 6 combos of JJ, you flip against 16 combos of AK (with the odds
slightly in your favour), and you're a big favourite over 16 combos of AQ. You're a slight favourite preflop. Add a couple of TT/99 hands in his range or worse, and we're looking even better.
Once that flop comes, you're only behind KK+, beat the rest, and he's not folding with the little he has left in his stack.