Only by those who believe the "official history" of him.
Well, yes, but that's the point. In order for it to be a commonly understood byword for a tyrant, as "Benedict Arnold" is for a traitor, it would have to be based in what's generally believed, not in secret knowledge that conflicts with common knowledge. By analogy, history tends to gloss over the fact that Benedict Arnold was initially one of the American Revolution's greatest heroes and most successful generals, until his own side screwed him over and his self-serving superiors robbed him of credit for his victories and left him in dire financial straits, driving him to change sides. But if someone well-versed in the historical details used "Benedict Arnold" to mean an accomplished and loyal leader, that wouldn't be understood by the average listener, so it wouldn't work as a byword for that.