He is '23 if he stays in Juco and graduates ....BUT he can transfer to a 4 year program as long as he has completed 1 full semester of Juco with a 2.0 GPA ... so he could transfer to UM for the Summer session of '22.
According to what I have read if he has attended JUCO for at least one full semester and maintained a 2.0 GPA he can transfer to a 4 year program ... so he WOULD be able to transfer to UM for the Summer session and practice.