Hypothetical situations tend to be a waste of time, because they tend not to happen in many lifetimes of any particular individual, and are best suited for freshman philosophy classes in college. With that said, I'll engage... and with having done no research whatsoever. First of all, this hypothetical dilemma is vanishingly unlikely to ever happen to me, because as an architect and urbanist, I'll be likely to be flying my M3 at 50 meters or higher. But if it did happen, then my split-second assessment of the "ghost in the machine" dilemma where nothing I do with the sticks has any meaningful response, it seems I'm left with two options: either a tap or a long push on the Home/Pause button. I'm not sure which will do what, but it's likely it'll either pause the drone or set it down at Home. If neither works, then I have no clue, as it's highly unlikely that any of the rest of the buttons would do anything useful, so I'd probably run screaming "DUCK!!" to the unsuspecting bystanders imperiled by my never-to-be-at-head-height drone.
With all that said, I have a question: cars tend to be about as intuitive as Mavic drones, in my very limited experience so far: the gas pedal means go, the brake means slow down, and the steering wheel turns one way or the other. Adding the third dimension adds complexity, but not overly much. No intention of disrespect, but how many on this list have read the entire manual of their car before driving? Full disclosure: I never have, and have undoubtedly missed many features, but have gotten home safely in spite of being not-fully-featured.
