I stand by my previous comment about the pilot having the final authority, and ATC not creating any more stress for the pilot than he or she already has. BUT:
I am also GUESSING that the FAA might have issued some sort of "guidance" to ATC previous to this event, for them to try and send warbirds away from populated areas during an emergency. There have been significant incidents in recent years; the B-17 that landed and burned up between (thankfully between passenger flights) is one of the more recent. The FAA has a mandate to prioritize public safety... passengers and people on the ground... over everything else. I love warbirds every bit as much as the rest of you, but an 80 year old airplane, on low-grade fuel, without the original infrastructure (whole squadron full of military mechanics and unlimited free spare parts a phone call away) is not exactly a low-risk proposition.
So although PIC is PIC, I can also understand why a controller might want to use whatever influence they had top get the airplane away from the city. A full-fuel B-25 crash into the wrong part of Vegas (bottom of a hotel) could cause thousands and thousands of civilian fatalities.
Another issue I have is that (unless someone can convince me otherwise) there is no reason whatsoever for that airplane to have been at full fuel load, on a hot day, with low-octane fuel, on a passenger flight. Flights to the canyon and back will require X gallons, and then you add VFR or perhaps even IFR reserve, and you can lighten the load on the engines, increase flight safety, and reduce maintenance costs on the airplane. Four or five hours of fuel is a convenience that became a high risk on that flight.
So the big question to me is... was that traffic controller subject to disciplinary action after this incident? If he was not subject to discipline, after clearly putting the safety of everyone in jeopardy, then that would tell me the controller was in fact following some mandate or effort coming from higher up (to herd warbirds away from the city at the first sign of any mechanical trouble).