Continuity mistake: The amount of foot dust changes from when Chris come back to when Kenan grabs some.
Continuity mistake: Bloodbath's lead disappears between Kel bringing him out and him chasing Chris a few seconds later.
Continuity mistake: When Kel throws the foot dust the first time, a girl at the back is coughing despite no dust meeting her.
Answer: He's simply enjoying doing it himself. Especially since he likely believes he can do it better than she can.