Yeah, it's mostly a tongue-in-cheek comparison :). The meta-point is that the entire online learning space has a small fraction of society's collective attention, scraping by against the popularity of a rap artist who will be forgotten in a few years.
This doesn't even go into the fact that people could easily passively listen to Super Bass in a non-active window while Khan Academy requires much more active watching from the user.
(i.e. I could have super bass on my iPad in my car while I drive somewhere as background noise but Khan Academy requires me to be sitting in front of my PC focused on it).