Well... not knowing the bar in question, I reserve judgement on that part of the issue (there are some I know of where you wouldn't want to wear a Rangers jersey or a Yankees cap for instance), but he could have changed the meal venue if that was the sole reason for concern. So I fear his problem was with the kilt itself and that he was sending you a message, however consciously or unconsciously.

He may suffer from Kilt Derangement Syndrome, a rare but crippling mental disorder.