I'm pretty sure hell would freeze over, if it were me, if I let people into my shop to choose wood, unless they were an extremely special customer. I think they may have other reasons. Trade secrets? Don't want to be bothered with work flow interruptions. Tours would seem to be a doable thing, but they have their reasons.
I just built a guitar for a buddy, who drove to puyallop, went to warmoth, bought the body. Handed it to me and ordered a neck (Warmoth) and I assembled his guitar for him. It's a beautifull Black alder body with a red perloid pickguard and a stupid reverse headstock strat neck.