Threaten to beat his ass in front of his woman if he don't back out of it?
J/K LOL.....
I know with some models of electronic ignition controllers, there is a "chip" or "pill" that can be plugged to limit rpms.... Not sure if it would work in the situation you descibe though. I've done that before, running across some choppy water & had the pump unload a few times. I just back out of it & slow down some.....