I will have to confess to ignorance as to the origins of kilt/Ireland connections, but I was under the impression that some of the Irish Regiments of the British Army did wear a kilt. Of course this may further explain the average Irishman's disdain for the garment...

I do take umbrage though at his contempt for Irish-Americans or Irish-English or Irish-whatever; what is the harm in someone wanting to have a link to his or her past? I think, especially in the case of Americans, it is a way for folks to broaden their world view and maybe realize that we (America) are not the only ones on the globe.
Just my two cents.