I recently moved to the Kansas City area, and also recently contacted BT for warranty service. I was astonished that they would refuse to work on my trailer since I did not purchase it there. I have subsequently had another dealer more than happily agree to do the work and the Airstream rep from Jackson Center has also been more than helpful in working the issue. At this point I am only waiting on the parts to arrive. It won't be done through Bill Thomas though, and once complete, I may ask Airstream what their policy on dealers refusing to take on warranty or other service.
Extremely disappointing that Bill Thomas senior service manager would refuse outright. This is NOT my expectation of how a credible dealer would handle themselves.
It may behoove the OP to call around in the area to RV service centers in the expected pick up and verify their availability to check it out and do any work. Likely that most anywhere could do what he needs done to ensure it's ready to travel.