I'd think he was over-qualified.
I was a nurse before I became a childminder. Was I overqualified?
I had to do specific childminding training and a whole host of other training in health and safety, food and hygiene etc. None of it related to nursing nor teaching.
Do you actually know what cms have to do to register and remain registered these days? Its not just a bit of pin money from working from home doing a bit of child minding like it used to be. The paperwork alone is horrendous and a royal pia. Learning journals, observations, child led planning, no time to be bored! (and a lot of it done at night and unpaid)
I know a cm who has more (and higher) qualifications in childcare, developement, special needs care, and other subjects than most of the teachers I know.
I would think a teacher would be a great cm, experience, patience, and ability to relate to kids. (and used to paperwork!)
Anyway he cant just quit teaching on Friday and start Cming on Monday. It takes weeks to become registered, house checks, training courses, first aid training, getting equipment together, PLI, house insurance, car insurance all need revising then waiting for the registration.
BTW I know a male CM through another forum, he is fab and has a waiting list. He is a great role model for the kids as well as extremely knowledgeable on child developement and done various extra training.