All right, from the pictures it doesn't look that bad...so if your painter guy admits that he doesn't have a whole bunch of experience and you knew that going in, than I guess I can forgive him for some of the comments he made, we all need to start somewhere...to me it sounded like either he lied to you or he was inexperienced...I'm glad it was inexperience.
If the car was unmasked 2 hours after painting it, then any or all of the other reasons for the paint coming off could be the reason. At this point, the main thing is you will know what to watch for when you repair the door...A razor blade can work if the paint has bridged but, you would need to be extremely careful and have a steady hand. Try pulling the tape away from the panel when your unmasking, that will solve most of your problems, especially if you unmask 2 hours after clearing.
As long as your satisfied, that's the main thing.