i personally wouldnt of let him spend the $400 to "sand the area" and repaint... whatever is CAUSING the clear to peel. is still going to be there if you dont go into the paint/primer and start over... what a n00b.
Also, just kuz the car has paint edges doesnt necessarly mean the car was HIT "bad" like he makes it seem.... it could of been anything, keyed, a shopping car got slammed into it, maybe a rock hit it, maybe a baseball? All of those things could of been cause enough to repaint the car if the paint chipped. Dont stress yourself.
I work at a bodyshop and i deal with s**t like this all day everyday, paint edges simply mean the cars been repainte at one point... it doesnt mean there was "serious damage"... my friend has a 06wrx with paint edges on every jam area, why? it got keyed, all the way around. So the point remains, dont stress.
It shouldnt be more then $1000 to respray that panel, and blend the door. Its roughly (just to throw out general numbers) about $350 a panel, + any misc things that may come up such as dents, paint problems... a good bodyshop wont respray a panel with dents in it, they'll fix um before respraying.
My best advice for now, peel away any "loose" about to fall off pieces of the clear, and wax the s**t out of that car... especially that area. Now that wont STOP it, but it should slow it down considerably.