Cincinnati was outmatched, as we all knew they would be. The point is, they did everything they could possibly do to qualify, and they deserved the chance because of it. They played and beat multiple P5 opponents (including a Top 10 win on the road), handily beat their opponents, won their conference, and went undefeated. If a team with that resume doesn't "deserve" to make the playoffs, then what is the point?
If there's no possible avenue for G5 teams to qualify for a playoff, then they should have their own national championship playoff. In what sport do half the teams in the league have no shot to make the playoff, regardless of what they do during the season?
There's not a sport on Earth, except for college football, where an argument is made that an undefeated team with that resume doesn't "deserve" to make the playoff.
TLDR: Cincy deserved the opportunity. If G5 teams don't have a chance to play in the playoffs, then there should be a separate league with a separate championship.