I think it's even simpler... You're a "real DJ" when you feel like a "real DJ," but at the end of the day it's a useless label. More important labels are "mobile," "club," "open format," "turntablist," etc that actually tell people who might want to book you a little something about you.
If you have an audience that seeks you out to play for them - you're a real DJ.
I suppose if you want to credit the cited article then - yes, knowing what to play next is part of how you create that. However, I like my broader one sentence definition better.