Are you saying that if your most productive employee were also running a side business (not side project), you would fire him out of principle? Or are you just

Are you saying that if your most productive employee were also running a side business (not side project), you would fire him out of principle? Or are you just assuming that the side business would make the employee less productive to an unacceptable point (a fine reason to let someone go, but that a side business would cause this is still just an assumption).