I'm not sure what kind of 'advice' you're looking for. Are you asking if you should report him to someone (I don't know who)? If you should confront him and tell him your opinion? If you should tell his students your opinion that you think this is wrong? Are you considering going back to train there again?
As far as I can see, it's not the kind of thing that's done in secret so there's nothing to 'report', and other than that it doesn't really seem to have anything to do with you.