The races prefering to solve their problems with violence in no way, shape or form constitutes a legal authority. I'll ask a third time then as so far you're pointlessly meandering.
You mean the Warchief that was using his absolute power as he pleased with no regard to any of his advisors? Yeah, no.
You mean the guy who put the guy in the stone hand, i.e. the absolute ruler not listening to anyone also by ignoring all of his advisers (and Garrosh as well)?
What does one have to do with the other? The Legion merely manipulated the Horde. The Horde owed them no true allegiance, nor were their actual subjects.
Except as Baine himself argued, the very words of Vol'jin you're referring to here warranted his death penalty. Making it clear as fucking day he had no such authority. You couldn't find a worse example if you could and your three prior examples were already terribad.
The capacity of people to break the law doesn't mean there's no law. It only makes the people using such a capacity of theirs criminals.
This isn't any more of a legitimate authority than a murderer solving their problems with another person by murdering them.
Which is a nonsensical position because even if that was true, "having a good heart" and "just doing what he thinks is right" (which somehow by pure accidental accident is always helping the Alliance and handicapping the Horde) is not a carte blanche to do as he pleases nor a jail out of free card for the consequences of his actions. Actions that include literal treason from any and all perspectives.
The Horde did when they accepted Vol'jin's nomination and swore to her.
The questline is only about Vol'jin sucking balls even as a Shadow Hunter (so that now he sucks at everything he has ever touched in his life) and only thinking it was the Loa that whispered to him, when in actuality it was some other entity, perhaps attuned with the realm of Death. But that doesn't negate the fact that he appointed Sylvanas. And him being wrong in his motivation is largely irrelevant. As @
Super Dickmann already mentioned in their reply to you, Blackhand was deposed in a Mak'gora. If false pretenses for appointing one Warchief were enough to dismantle the legitimacy of a Warchief, that Mak'gora would have been unnecessary and Orgrim could have just exposed his findings to the Horde.