What a waste of energy over this "Hammerhead Torque/Flick Roll Hammerhead Torque/Flick Roll Thingy" which is neither aerobatic maneuver terminology or BFM/ACM terminology. The supposed maneuver is used by airshow performers and doesn't exist as an air combat maneuver. As far as turning off the engine, whoever came up with that, it is an absurd action the NO actual pilot would ever do intentionally. In an air show environment and an air combat environment, there is NO valid reason to shut the engine down because THERE IS A VERY REAL POSSIBILITY THAT IT WON'T RESTART. A pilot who considers shutting down the engine because there is some imaginary reason to do so is just plain delusional.
Oh, and someone please throw up Bob Hoover's engine out airshow demonstration which is an amazing demonstration of energy management, which is rarely discussed in the forums. But that's a whole other subject.....