Assuming it's torqued that tight and the torx trick doesn't work, It's a relatively small job to hacksaw and remove it.
If I were in the OP's situation, I'd take it to Dlask or bits of pieces for example and ask them to redo the barrel install. (btw I haven't used either, just know they have a good reputation).
I know someone that is very handy that botched the install of his own 10/22 heavy barrel similar to this one because it was tighter than he thought. Perhaps in a hurry he went straight to using tools that marked up the barrel when tapping wasn't working. Same sort of thing as the OP got. The added complication is that the extractor groove has to end up indexed in the right spot.
If one slows down and does some preliminary measurements, the whole mess can be avoided with a few minutes of emery cloth on the ID of the hole before the attempt is made.
So I suspect the gunsmith rushed it, then tried to hide his screw up. He should have known that powder coat was not going to like the vise treatment, because once the metal underneath is deformed it lets go. Didn't put in soft jaws or, they couldn't hold the barrel I suppose.
And this all makes the OP's gunsmith look bad on this simple project. Certainly one I would avoid.