Check HealthGrades, Vitals and Wellness. There is also Yellow Pages which is different from Yelp.

If he is not registered anywhere, it IS a good news.

Also, keep in mind that it is a responsibility of those who consider seeing him to check if he carries a license. If they do check they will find out very quickly that he lost his license due to a disciplinary action. If they don't check it is on them. It is not your responsibility to exercise the due diligence for them. So, it's not like people don't have an opportunity to take care of themselves. They do. So, let them do it.