It's not just about him fighting for the company, it's about his name automatically giving the UFC publicity. People think of Conor, they think of the UFC which is good for the org. If he were to leave, that would gradually change, especially since he's likely going to promote himself for some Mayweather type fights. He can earn still money for the company once he finally stops running.
Cutting him would probably be the right ethical thing but when money is your main goal, ethics are the first thing to go to the wayside.