Not the first time I have heard of this kind of thing. The company considers this an “alteration”. They do the same thing with trailer hitches. If you attach a hitch and tow a trailer with your HD, the warranty is invalidated. The dealer itself has a lot to do with how things work out. Does the trike rider have a relationship with the dealer? Some HD owners do not bring their bike back for maintenance, ever. Others, like me, bring it back for extended warranty matters. I suspect there is more to this story. How difficult would it be to unbolt the flag mounts before bringing the trike in for service?
They consider putting on decent pipes an alteration.
We give back the stock parts so people can swap back out the trike kit for warranty repairs, if they need them.
There’s a way around everything...:)