[aaronbeen]

I think you should have gone all in to isolate the short stack. He has a very low M and you described him as desperate so it seems safe to assume that he has a wide range of hands and playing with your aj has positive expectation.

If you call and someone else plays you are probably going to be priced in and it is unlikely that you will fold. I hesitate to say that you are totally committed and if there is any flaw in my logic it is here. I get the sense that live play is much less aggressive than online but on pokerstars or something I wouldn't be able to put a reraiser on aces or whatever and fold getting good odds. (How good your odds are likely to be depends on the rest of the stacks at the table. If they all cover then you aren't going to be priced in as well.) Still, calling 1/4th of your stack and then folding seems really distasteful.

Given that you are somewhat committed by calling, your hand is obviously not strong enough that you want to encourage people to play with you. Move your chips in and scare off aq, jj, maybe even ak or qq from a weak/tight.