If they're what I'm thinking of the green ones will score stainless steel, so consider testing first. The blue non scratching ones may not be quite as effective, but are a lot less dangerous to your pots, pans and other kitchen equipment.

What kind of nonstick coating survives the high temperatures present in a grill?

Probably a ceramic coating.

Just don't use a scotchbrite on a hot grill.

Ha! There's really little reason to try "cleaning" a hot grill.

I can come up with three reasons. First is to remove beef residue before cooking chicken. Second is to prevent chicken from sticking - a clean grill with fresh oil sprayed on it works best. Third is that, when running a grill for a number of hours at a time, you generally can't afford to shut the grill off to clean it.