I think you adopt a worst-case scenario. I've read many times of both combat and civilian engine restarts in midair. It's as common as starting the engine in the first place. If you have no problems (i.e. combat damage) and willingly shut it off, there's no reason it won't restart again, if it was flight worthy when you took off.
If it's at the point it won't start up, you probably never would have got airborn to begin with, no?
P.S. Skorp, I don't think the thud had a 600mi range on full gas, let alone glide!
You are absolutely right, Krusty. Restarts happen every day. But, the pilot who doesn't plan and prepare for the worst case scenario isn't going to be around for long. Aviation out in the real world is very unforgiving. An old saying states: " There are old pilots and there are bold pilots but, there are no old, bold pilots". Temp fate in aviation one too many times and and you are going to pay dearly for it. Intentionally shutting down an engine in an air combat scenario will put you right at the front of the line.
The point being that it is illogical to intentionally shut down an engine in a combat scenario (real world). Yeah, obviously the engine(s) started up fine on the ground to get the pilot where he is going, to this point. Shutting down in combat is asking for that random point in time where the "where did that come from" mechanical failure, vapor lock, etc. that has never happened before just happened and the steely eyed fighter pilot is now sitting in a large refrigerator with wings. There is NOT a valid or logical reason to shut an engine down in a combat situation. Speed is life and speed comes from a well maintained and operated engine(s). If one needs to reduce speed, slow down, force an overshoot, etc. there are other time tested options that work effectively, i.e. BFM, speed brakes, engine(s) to idle etc. It comes down to pilot skill or lack thereof. Shutting down an engine to achieve victory doesn't demonstrate a shred of pilot skill.