I wouldn't have expected you to do anything differently if I were the customer in this situation. If he didn't request a swatch (or link you to the tartan he wanted if no swatch was available or request yarn samples if no link and swatch were available, etc.) he brought this on himself. You wear a lot of hats in your business, but I do not believe that "Mind Reader" should have to be one of them.

If a customer is going to represent himself to you as someone who knows what he is talking about, he should make certain that he knows what he is talking about. If he is not certain and does not ask important questions, he gets what he asks you to provide. There is no shame in asking questions.

In any event, this person took delivery of a nice kilt. This is both a good learning opportunity for him and a good opportunity for him to start saving for a second kilt.