I make AR barrels fairly often. Turning them down correctly does not harm them at all.
Just take light cuts and don’t heat the barrel up much.
It takes a bit of time, but I have made some super accurate ARs with very light weight barrels on them. I light barrel heats up faster than a heavy one, but for short shot strings they can be every bit as accurate as heavy barrels.
You do need to leave the boss under your “gas block” ( front sight mount) full size if you want to retain that sight, but it will do nothing to harm the accuracy if you remove metal on both sides. Think about the fact that ARs have flash hiders. That’s a “glob of steel” that’s on the end of the barrel where it can vibrate the most, and they don’t harm accuracy.
It is true that such a barrel may make the rifle a bit more finicky about ammo. If I were doing it for myself, I’d go with a free flat tube at the same time. That can solve several issues that may come up with GI handguards and light barrels. Don’t use the sight mount as a sling attachment. Use the F.F. tube instead and accuracy will be as good as it is now.