I'd be curious to see exactly what they're asked to do, and how many people are on this board. I work in a business that recruits similar "boards" all the time. Sometimes it's a way of thanking people for support, sometimes it's a way to get more money out of them, and sometimes they're actually tasked to do things. Or any combination of the three.
I know I'd be very interested in it either way. He should definitely do it.