The joke is not that they don't make dubstep (which they both do, only deadmau5 isn't really a dubstep artist), but that he says that Skrillex and deadmau5 make the best dubstep he ever heard. And that pissed me off.
Go listen to Flux Pavillion already you cunt!
Just personal preference. From a "commercial succes"-point of view, Skrillex does make the best "Dubstep".
On the other hand.. all hail the old, minimalistic Dubstep without stupid female vocals, catchy refrains & house sounds everywhere. Although I like some of the Circus Records Stuff (e.g. the old Doctor P songs), they also make quite commercial Dubstep nowadays. :<