No it has not. What is debunked is that he didn’t fire the Zuni missile. That came from a Phantom II. McCain did make it worse while saving his skin. Then he left the ship as they dealt with the aftermath.
That is a fact.
If he purposely wet start his engine (a thing wiseguy pilots did to piss of pilots behind them) and the wet start caused the rocket to ignite, then he did cause it.