I think there is a way to do that. Having his doctorate is reassuring, and it is possible that the instructor sees a real potential for performance there. I will think on it more. One possibility could also be like above; if the instructor helped him get into a very strong performance undergrad, and that was truly his life’s passion, he could then spend the year after graduation in auditions for major percussion positions. If he lands one then, it could become his career. If not, he could then prepare for an education-oriented graduate program.
But there are probably other possibilities. Again, he is young. Maybe you can also feel out if this switch you mention was brought about by pressure, even subtle or atmospheric, from the instructor. If he had stated an interest in education, I wonder what the deal really is. Young students can sometimes feel a pressure to adapt to strong-minded instructors, even if the latter are well-meaning and highly educated.