"One of the things this thread illustrates well is not every student is a good fit for every teacher".
You sure got that right. As for me, I'm fairly liberal and not as rigid as when I first strarted teaching. While developing, I did have my share of bad fits. Over time, I learned to find ways to assist the student as best as I could. However, what we are discussing is a young man who must adjust to the dictates of a new trumpet instructor.
I think someone said it best when they said, "You can't fill a cup that's full". My suggestion, fake it if his cup is full. His job is to get a degree.