He gets in with the right crowd to seize the moment that he can snake them and flee.

Jimmy pushes him off a banister, he sticks around - he knows where the power is going to land.

Manny chokes him, prolly didn't do it for long, and he gives up Jimmy (which he prolly reluctantly did but he also knew Jimmy was out of town so he figured the wife would be collateral damage...and something to keep Jimmy busy while he set up his plan to rob them all via Van Alden).

Mickey plays weasel very well, unassuming, harmless (though he has used a pistol on this show), weak...until he runs off with your 300K and you never see him in AC again. lol