The average dry film thickness of these things is going to be a few mils total (~100% will be 2-6 mils). So very thin.
Pretty much any indoor coating is not going to resist UV well, whether it yellows or not. The acrylic based resins i guess will be okay. The reason all the lights in houses are UV filtered is not entirely about safety - the amount of UV radiation they would produce is fairly miniscule from a human perspective - but if they weren't filtered, leaving the lights on in your kitchen too often would likely, over the course of five years, be really bad for the cabinets, floors, walls, etc.
I think this in practice, the killer. Even if you could deal with plastics themselves, there is just so much you will now have to protect or change.
If you want to deploy UV in a specific space (think conference room or hospital ward), I don't think the problem is that hard. There are coatings you can put on top of existing plastics which protect them from UV light. However, I imagine that customer education around managing risk to plastics is going to be a key issue for UV companies if they are to succeed.