Do you have pictures? How is the tank set up and how are you keeping the humidity up in the tank?

To start, I would temporarily move him out of the tank and into something where he feels more secure - if they feel too exposed, they won't eat. At his size, a sweater box would be more than adequate. I would keep everything pretty simple at first. Crumpled newspaper is good to let them 'burrow' a bit. Use a nice, big water dish (if they can fit in it, even better) and keep him in a quieter area just to let him settle in a bit. I would wait a week without handling (unless you need to clean it) and then offer food. Make sure the rat is nice and warm. I do have a few that don't strike, but will just eat on their own if I leave food with them. Just an additional note - sometimes, especially in the winter, the scales can be dented. It can be really really hard to get them perfect. As long as he has fresh water available and can rehydrate himself, I wouldn't be too concerned with that part yet. Getting him eating is the bigger worry so far.

Anyway, I hope that you can get him eating. For the attitude, they do generally grow out of that especially when they are fed well and feed secure.
It's great to hear that he is with someone who is going to work with him and get him healthy!