I think it goes to that old debate about what is historical, traditional, most common etc, and, if and when does one become the other. I think it has been established that white hose are a result of surplus military supplies and kilt rental outfits. In North America we don't have a firmly established tradition of the kilt. What we see most often (white hose, ghillie brogues etc) from the rental outfits became OUR visual "normal". I suspect that your brother is not wanting to look abnormal in North America regardless of how non traditional, in the Highlands, he may look.

Rex (Thisledown) and I had a discussion in my early days here where he put it in context for me. Essentially any culture can adapt, or adopt, anything they want from another culture, but it is only that new cultures version of it. It doesn't change the original tradition. A kilt worn in North America with white hose, ghillie brogues, a fly plaid and PC during the daytime, is how a kilt is often worn in North America. That doesn't change the accepted traditions of how the kilt is worn in the Highlands.

The rub comes when we (or the marketeers) promote what we are wearing, or they are selling, as traditional in the country of origin, when it is far from the truth.

I like AKs suggestion, allow your brother his choice of hose during his big day, and provide him with an opportunity to do it differently at his leisure.

Best regards,
Brooke