The trick is to hijack him when he's in a position where he is blocked somewhat then when you throw him out he doesnt go so far and will be easier to reverse on him with his car
target/session bouncing does break you out of the black screen but it doesnt make the vehicle youre in go into the MOC. Your character just gets out the second your friend pulls you into MOC.
Ive noticed that if the second heli crashes too close to the invincible one he will get scared and fly away so I always try to hit right on dpad as far away from the helupad as possible. Also if I go too far from the building he will fly away so as soon as you spawn call your mk2 and speed up there.