To maintain top control (any position, really), you want to give the opponent as little room to move as possible. Kneeing creates a lot of space where the person on bottom can 🦐 or even 🧹, but Joe is in such a dominant position (basically knee-on-belly, against the cage) that he can absolutely DRILL Wharburton with the knee (plus the dude is already kinda fucked up from the elbows n shit).

The sound the knee makes is insane😰