If nothing else, maybe the power of vigilantism can help?

Travel to Mor Dhona, and if he follows start making /shouts, including, your <pos>, that you want him to leave you alone. Hop on a fat chocobo/goobue/Magitek mount and sit on top of him, and also ask others to help sit on the guy.

I doubt the threat of mass /blisting from the community will deter him, but it could end up becoming a big joke for people to sit on that guy specifically. If he's always the butt end of the joke (so to speak), it may drive him off.