Unless there is some weird bug causing this for you, it is all about the launch force.
The dudes explode when:
- They hit their head to wall at certain speed (unless they are using a hard hat like they do on the first levels).
- Their limbs get embeded in the walls. Mostly just a safeguard against glitchy physics situations bu this happens when launching them at too big of a force or when they get lodged between closing doors.
- Their limbs joints get torn apart too much. Only happens when they are pulled by a door they're attached to.
So most likely you are just using too much force. Try using less and less until you find the sweet spot where they stay alive.
Thanks for the interest and sorry about the long answer delay!