Not sure I agree that Hooker was ever "hot garbage", though I suppose that is a relative term.
I think it's based on the idea that both guys have had the exact same amount of time being coached by Heupel and his staff in this system.
One guy looks like an All-SEC caliber QB, and the other looks like he'd have trouble beating out Jarrett Guarantano in a QB competition.
One guy has shown himself to be extremely accurate, and the other lost his job, due in large part, to overthrowing wide-open receivers by 5-7 yards.
One guy has shown himself to be an extremely capable runner who puts it all out in the field for his team, and the other has shown that he's scared to get hit, to the detriment of his own team.
Why don't I believe it can happen for Milton? Because he has not shown a willingness to fight for his own team, let alone the QB job. He has Hooker in his way, this year and next, and I think he'll be recruited over in the meantime. Meaningful playing time, in his future, will likely be sought elsewhere. The writing is on the wall for him, I'm afraid. In addition to falling behind in the current battle, I think he lost the support of many of his teammates, as well.