There is a TON of stuff that can go wrong swapping to tundra brakes, IF you don't typically wrench on stuff. He has clarified he typically/always takes the rig to someone else it seems for work.
Imagine doing a brake swap with no tools or knowledge? Sure you can remove a bolt. Can you remove the hardline without flare wrenches? What about when you strip the fitting using an open ended wrench? Can you bleed the brakes by yourself when you don't have the tools?
If this job isn't done properly, which it's not "hard" more of the problem having multiple area's of knowledge, you can cause a serious accident. To answer your question, I cannot see a dealership installing these. As stated, liability on them modifying existing brake components, even a dust shield is never in their interest.
If you were to already have these installed, I don't see any reason they could/would deny service if the vehicle safely drove into the building lol. They just don't like anything but what "works from the factory" at the dealership typically.