Plus I have had him like 2 or 3 weeks and I have never seen as much as peck on a rock or eat a single piece of brine. However he is fat and healthy. Is there anything at all I can do to get this fish to swim in the front more?
Give it more time, it can take angels quite a bit of time to overcome their natural wariness of being in your tank as opposed to the ocean. Without coming down on you (I blame the collectors) I have a problem with Adult breeding stock being removed from the ocean. This is one less fish in the ocean to make little potters angels and Adult fish have a pretty high mortality rate (compared to juveniles and adolescents) IME. They just have a more difficult time acclimating to captivity. If it doesn't start visibly eating, you may be in trouble, it is probably living off of hitchiker sponges and algae on the rock, this will run out eventually. I wish you the best of luck, mine has always been miserable with Potters angels. IME, they are a very high maintenance and high anxiety fish.