Let's ignore if you think he "deserves" another year for whatever reason you choose, and just look at this objectively. What is the absolute best-case scenario for next year that is actually plausible?
Looking at the roster, Betts, Frank Mitchell, Grayson Grove and Asuma will be the only returnees. Then add in three freshman who based on their rankings and other offers likely won't be big-time contributors out of the gate. That leaves up to 6 spots up in the air. If we go off of CBJ's history on the level of player he'll be able to attract, we can reasonably predict what those players will be like. Also looking at how long this year's team took to "gel" and in 25/26 relying a ton on "one and done" transfers yet again (likely also acclimating to the B1G from a lower division), what will be the performance of those guys the first 1/3 to half the season?
I would argue the absolute best case scenario is a 8-12 conference record with a bunch of cupcake wins in the non-con. If all things go right, at best it puts us on the fringe of the NCAA's, but very likely on the outside looking in. While there is always a chance, I have a hard time believing there is better than a 5-10% chance next year's team is better than this year's team. At which point I would say, what is the point of keeping him on? If you're rolling the dice on a 10% chance you're better and a fringe NCAA team, but the much higher likelihood is further alienating and driving away the fan base, is that really a risk worth taking?