Remember, there is no right way to stage manage, just wrong ways.
One person can easily sit in judgement of another stage manager and their style.
Yes, there are things perhaps a stage manager maybe failing, but as a student, it seems like that is what they are paying for the opportunity to learn, fail, and grow from it. (If this was a professional environment, it would be something different.)
Now, as ASM, in this situation, I would do everything I could to support the PSM, doing the best job one could do, and see if there are tasks that the ASM can take over the PSM - maybe part of the issue is they are overwhelmed.
But hard to give specific advice without specific issues being raised.
If his unprofessional behavior, for example, is hitting actors with 2 x 4's, then I was suggest taking away the 2x4's.