Since his hygenist works for him, she must have his permission or he hasnt figured out she is feeding them. The elderly couple does it on weekends when he isnt there. It appears they are getting enough to eat. I would not feed them. As for trimming food, have the treats in plain site when your doing it if he see's you giving food it's because the cat needs to be still while your trimming.

I would be careful with him because he could make life miserable for you and your cats.