I hear what you are saying but there are two problems.
First, the NCAA granted this one time waiver and it is unlikely that will do it on an-going basis, even for charity, as it would give the team and extra game and an unfair advantage. I really don’t believe you can make it an ongoing yearly charity exhibition game. If the series resumes it will have to be as a regular season game.
Second, you assume MU is a top 25 team which at this time is by no means a certain thing; MU will ride the Porters and other quality recruits for all they are worth and in 3 years Martin moves on and MU goes back to being a dumpster fire.
Just my opinion on the subject and I don’t claim to be right.