It seems pretty stupid to give progressive music such tight restrictions. Doesn't that sort of, like, hinder progress? Correct me if I'm wrong, but at its most basic definition, progressive music is just a combination of several genres (which initially were classical, jazz, rock, and folk). I've just updated my defintion to include contemporary genres (like metal and electronic music). If you look at most of Ulver's music, you can definitly see all those genres in use (well, maybe not jazz so much).
I guess we just have different ideas about what it means when music is "prog."