I DO NOT know about the inner workings of an RV dealership, but I do know about auto parts. I owned an auto parts store that offered a nationwide warranty on most all parts sold.
If someone purchased an alternator in Vermont, and it want bad in Florida, the local store had to replace it. That is not a problem.
What bothered me was my money for that replacement was often tied up for six months before I got re-reimbursed for honoring the warranty.
During that time that money was not available to invest in other inventory to make a profit with.
If this is the same in RV dealerships, I can understand, but do not condone, their reluctance to work on a unit that someone else sold and made the profit on especially if they are also tying up their working capitol in it.
