Can plain old whole wheat or other whole grain flour be used instead of the white whole wheat?

Yes, you can- with a few potential adjustments. Regular whole wheat flour and "white" whole wheat flour are essentially the same kind of flour. The main difference is the color, although some folks say the white variety has a milder taste as well. You will need to add more liquid in as well, as it says in the remarks section. I'd also highly recommend letting the mixture do that chill, so the bran has some extra time to absorb liquid as well. Your scones will be darker if you use regular whole wheat flour instead of the whole white wheat or all purpose flour as well. If you want to use other whole grain flours, I would suggest using them in a mixture with regular wheat or all purpose flours though, because you still need a certain amount of gluten to form so your scones have structure.