Of course, but in a general sense--outside of pandemic years--I think he has a point. ND usually gets applauded for playing a "tough" schedule, when in reality all that really means is that they don't play FCS cupcakes. It's not that unusual for them to play 0-1 games against top 10 teams, while they get to beat up on the second tier teams from p5 conferences.
You put them in a conference and they're still very good, but would have a difficult time making the playoff. Maybe comparable to a team like Penn State (excluding this year). That's not even factoring in that joining a conference eliminates the last thing making them unique, which is their independent status and accompanying NBC deal.