I would encourage about twenty kilt-wearing friends in Wisconsin to come and browse for a couple hours one day just to steep him in the culture. (If they are big and hairy, so much the better. Quiet, subtle intimidation can be ok.) Otherwise I would address the issue with the higher-up who gave you permission. This guy is a bully. On the one hand we as people get along by avoiding conflict. On the other hand the culture he stands up for has rejected bullying and is taking it really seriously. You should avoid conflict and avoid losing your job. WE should see that he stops bullying people.