I'm in the same boat as Emilien Wild, Lyle Waldman, and David Rockwood on this one.

If a player wants to allow their opponent a minor backup, that is entirely up to them, any REL I'd allow it if they both agree to it. Be it comp or regular though, this isn't a missed trigger or anything we really help fix if the opp doesn't let them rewind., despite the reality of magic, all players are assumed to have read and/or agreed to the terms of the MTR when they join a tournament. This may be a temporary feelbad moment, but it's also a learning experience that will help them in future.