This is a tricky. I am not in any way excusing weasel words from Musk. If he says a car wasn’t on autopilot when the accident happened, because it was turned off a second before, then, yeah, he’s basically lying.
However, ignoring what Musk may say, there is nothing nefarious about the car turning off autopilot a second before the crash. When self driving gets in a situation that it can’t handle, it will turn off. That situation can be something as simple as the autopilot thinks it’s too close to another object. If the driver isn’t ready to take over immediately, there may be a collision.
I’ve had my full self driving turn off due to situations it got itself into. For example turning onto a street, and getting the front end too close to a parked car. No collision, because I’m paying attention, but the car freaked out. Self driving couldn’t have turned off or warned me earlier, because that parked car wasn’t too close earlier. Obviously, not getting too close to parked cars should be something it takes care of before it gets too close.
Other times it has gotten confused about the lanes, and turned off.
As for emergency vehicles, as far as a I can tell, Tesla’s full self driving doesn’t do a damn thing when it sees one. I recall the beta release notes mentioning something, but I’ve never seen any reaction in the car from flashing lights.
If nothing else, flashing lights that seem to be on the travel route, or approaching from behind should force the driver to take over. Better, obviously is to have the car do the correct thing, but until that’s ready, punt.
What I’d really like to see is that all emergency vehicles have transponders that publicly announce their current location and destination when their lights turn on. Then in car systems can monitor that, and know that there’s a fire truck approaching on that cross street, even when it’s out of view.