Hahahaha! I bet you can get it out. If you're super, super careful, you could drill out the screw or try and get it out. I bet you could.
He has to watch out because the motherboard plate is aluminum any wrong and that's that.
Maybe he can loosen the rest of the screws (if he hasn't already) and turn the stuck screw (IN THE LOOSENING DIRECTION) and maybe the standoff will come out too then just replace the standoff and screw.