My little guy ate all his lunch today after first refusing to touch it. He later yelled for seconds! I think you guys are right, I just need to do my thing and not worry about the parents but realize that what they are doing will impact him but hopefully I can "un do" their damage as he spends more time with me. Sometimes I feel like we are in a divorced relationship with these families. They are the fun, carefree parent that lets them eat what they want, go to sleep when they want and do what they want.
Perhaps you are just what he needs. Children need rules and structure... if you're the one providing it for him than in the end you will most likely be the one to win his respect.