Back in the 90s when Harley came back real strong, HD corp got very protective over co-branding. Indy bike shops, tattoo and leather shops were buying HD t-shirts and having their info printed on the back. Authorized dealers had been doing it for years, but even they weren’t allowed to do it anymore.
When I bought a Sporty in late 1999 the dealership had local T shirts, and never stopped carrying them. Maybe the MoCo required their blessing on the designs?