Only Dave could say. But I’d like to point out that if the white point isn’t D50, well then he can’t call it ProPhoto RGB. Cause that isn’t how it was spec’ed.
Indeed. However, I'm loath to bother Mr Coffin with it, he probably only gets a kajillion e-mails a day about his excellent brain-child. Is "ProPhoto" a registered name of some sort, to your knowledge? All I've found is Kodak's ROMM White Paper which doesn't use that name at all. Take your point though, it is a little confusing.