More than likely the guy's way of saying "take your silly a** project and go away"...... Body shops live on bump repair quick turn jobs and if they needed a frame off once in awhile at that price they would not need many of them.....
A friend of mine has a small shop 2/3rds full of the time consuming low budget jobs that looked semi attractive when he took them and now are in the way of his making some badly neede money from winter crunch stuff he can't get in the door....
Of your 15K quote it would be interesting to know how much of that was figured as materials......