My nephew quit his job in Michigan because his boss was overbearing and intrusive
He worked as an asst. mgr. at at 3 diff. Burger Kings afternoons and evenings owned by same guy (one was 40 min drive away). He would stay an hour after closing (2am) to clean up - usually without pay. His Manager would call him in the mornings, even on his day off (5 hours later when he was sleeping)to complain of any little thing he had missed. She also called on his day off many, many times and demanded he come in when other workers had not shown up.
He has his 2 yr. old daughter on his days off and had to find emergency child care and lost his time with his daughter to go in to work and changed his days off around these days. One day he was wrote up at 10am because the floor was unclean. The restaurant had then been open for several hours and had had lots of traffic by then. He had been promised a bonus and raise in pay 6 months ago but never got it. Also, he was scheduled to go on (paid/earned) 1 wk. vacation the day after he quit - can they withhold vacation pay legally?
No, I do not believe they can withhold "earned vacation time legally. You can visit this page at Michigan's websit
for further details regarding unpaid wages and vacation pay.
As to whether he had good cause to quit and will collect unemployment....it's possible, but I can tell from your account that the state will more than likely need to investigate by asking questions of both parties about any efforts he first made to preserve his job .. even if that meant exploring his rights as an employee as to being relevant to the employer's actions
.. especially if he was a non-exempt hourly employee.