You have conveniently compressed the timeline down so as to obliterate the different stages over the past few years.
Never said that the last staff didn't regret it. They did. And SINCE THEN, Thad lost weight and put himself into position to be able to do more than just 3rd-and-short.
"He wasn't asked to leave because everybody was hurt"? Sure, maybe two weeks ago. But not "everybody was hurt" six months ago. At a certain point, Mario's staff DID feel like Thad was serious about improving and serious about contributing.
It's not accurate to sit here with 11/16/2022 knowledge and then act as if today's fact-pattern applies to the past several years equally. Thad is one of several players who promised buy-in, who promised commitment, who showed signs of life, and who has now regressed.
Now, if Mario knew in January what he knows today, Thad would have been Nesta'd before Spring practice and we would have taken another RB from the Portal EARLIER in the process.
EDIT: Please keep in mind that Mario could have just booted guys off the roster under the NCAA's first-year-coach exemption, and we had UNLIMITED IC's to be able to replace anyone up to the scholarship limit of 85. So there was NO INCENTIVE to keep Thad in the spring if Mario honestly felt that he was not going to improve and contribute.