Well I suppose it wouldnt have done him any good to leave it in?
Maybe, maybe not.
The stinger is serrated and the barbs face backwards (like a fishing hook) and are on both sides of the stinger. So when pulled out the barbs tear and rip on the way out making the wound much worse. Plus when you remove a penitrator, it opens the wound and allows blood to flow freely that was held back by whatever was in you.
We are trained as medics to leave whatever is penitrating in the patient no matter where it is (thigh, intestines, eye...) and secure it so it does not move or get bumped on transport.
But like I said above it is a human's first reaction to pull out whatever just jammed into you.
Do I leave it in or take it out?!? Do I leave it in or take it out!?!