Actually, if you bring the grill to 600F or higher, and hold it there for 30 minutes, it will destroy the proteins on the grill. But if you have anything on the grill while you do that, it will no longer be edible. The clean cycle of a self-cleaning oven will do the same thing, burning off any gluten. FWIW.
At a restaurant one time I asked if there was a shared fryer, the nice girl there said yes, and even though a lady told her one time that she is a nurse and the hot oil burns off the gluten, she doesn't think it is safe. I commended her for having some sense, and then told her that. At the end I added, "Since the smoke point of the frying oil is well under 600 degrees, the gluten would only go away if the restaurant burned down." Got a laugh out of that. She still works there and I try to go on the days I know she usually works.
Edit: Bad grammar