The muzzle threads will not be affected by shooting, but are extremely vulnerable to damage by bumping hard objects and the protector should stay in place.
There is a product called "RockSet" intended for high temperature applications that is often used to anchor muzzle devices and would stop the thread protector from moving once applied and installed.
If your friend wants to sell his threaded barrel and buy a standard barrel, I'd be interested in the threaded barrel because I have a suppressor I'd like to use with my CZ's. I use it on a Colt 9mm carbine and a Sig and have not been able to find a threaded P-01/PCR barrel in stock anywhere.