MI landlord tenant law, tenant's rights against landlord that threatens to lock out tenant

No. He cannot change the lock without court approval. In fact, YOU could change the lock, and he would have to go through the courts to remove it. You could also try filing an immediate harassment charge, trespassing, or any number of other charges against the landlord. When it comes to these matters, tenants tend to have the upper hand.

Michigan has a landlord tenant act that protects tenants from unlawful conduct on the part of a landlord.

There is also an anti-lockout statute in Michigan which prohibits the landlord from locking you out of the property.