Gad, do you feel like this happens every time one of these threads comes up?
Yeah.Same rumors same conspiracies. One point in it. "IF" McCain had in fact left the ship it would not have been for reasons assumed. After a fire of any seriousness those closely involved will be taken aside and have a nice long talk with what was in the day called NIS. Separating ones who may have witnessed events and doing interviews before it can be discussed {contaminated} with others makes for a more clear investigation. As for leaving the Flight Deck and going below? He would have went to his assigned GQ station and awaited orders. In his case a Ready Room.
Something else to consider that's kinda harsh but to the point. Enlisted are the primary Fire Fighters onboard ship not officers and especially not pilots the Navy has invested perhaps millions into. Officers including ships company were generally found in more secured spaces during emergencies.
I was first on scene in the Fire Dept on my ship for a storeroom fire which involved several decks. I also with a shipmate in my division who was also TAD to the fire department discovered it. NIS ask specific questions not as such to accuse but to find the cause. NIS actually held a class with us about spotting fire bugs on ship.
You're right about the O2N2 plant. People fear nukes that were kept on carries when in truth the LOX Plant was a disaster waiting to happen. The guys that ran it on my ship were MM's from my division.