Not completely true. I'm a TDI HOG Regulator Service Clinic instructor. This is a class that is sanctioned by HOG through TDI and does teach how to service HOG regulators. I'm teaching this course again in about a week and a half.
+1
The Hog Repair Clinic is a two-day affair and it does cover how to service your regs... as far as I know, TDI and HOG are the only companies to allow users to learn the basics and buy the service kits.
Course is $250 which includes a service manual