It seems you're arguing that Coppy was some kind of fall guy. I don't think that's the case. If the reports out there of what the Braves were doing are true then Coppy was up to his neck in it and he deserved to be fired.
It's possible that Hart and others were involved and are trying to hang all the blame on Coppy but that doesn't mean Coppy was fired to save face. It just means that others are hoping that sacrificing one of the guilty is enough to appease MLB.