Well, it's a pretty preposterous notion. The only way he can see what is going on is to coach? There is no other avenue? No other means to communicate with people, observe, and see what needs to be changed? That isn't true of any other GM.
I might as well say he should be fired immediately, and I'll say this because, if it's true, he isn't doing his job properly and clearly doesn't know how. I don't think that's the case. Even if I'm unhappy with the way he's done his job lately, he can clearly do his job, which further points to how outrageous that claim is.
Sure, it's different, but it isn't the only option. The resources at his disposal to find out what is going on during games, on the bench, and in the locker room are significant. If he needed to see it, it means he wasn't trusting the people he could have talked to, or he simply wasn't bothering to talk to them. That's also concerning to me. There is simply no reason he should have needed to be behind the bench to see what was wrong, and him suggesting that he needed to doesn't sit well with me. It definitely doesn't speak well of his ability to manage the team and the personnel on it.