I had bowed out of this about a week ago as I was making too much out of it. To answer your question-if I were these twins, yes I would. MR was the coach who allowed them to walk on to the team. Even being a walkon at Nebraska has life long perks in the State. Looks great on a resume. I would thank the guy that gave me that opportunity. Common courtesy and just being a decent human being should dictate that.
Every coach we've ever had has 'allowed' walk-ons. Don't try to make a saint of MR.