Aw, what a killjoy. I'm pretty sure that kilts have been worn by Scots for most of their history, and probably haven't been much worn in Ireland-- but so what?? If someone likes one of the new Irish tartans and gets himself a kilt in it, that is all to the good! The tartan designers and kiltmakers get business, there are new nice tartans to look at and enjoy, and more folks are wearing kilts What's not to like about that scenario?

(And pssst-- a slew of Irish came to Alba a loooong time ago and settled there. It's nice to get on with your relations, however distant they may be.)