Continuity mistake: Just before and when the president it in Rigby's The clock keeps changing time.
Continuity mistake: When the President is in the shop and the tower of Orange Soda is about to collapse, watch Kenan. He puts his arm through the display to make it collapse.
Continuity mistake: In the episode when the president comes into Rigby's, near the start Kenan fixes the slush-o machine, but it doesn't work, and slush-o sprays all over Chris. Afterwards, one of the slush cups on the counter falls over. After that, the cup keeps on vanishing then reappearing.
Continuity mistake: When the President is being crushed in the Oval Office, Kel opens the sliding door. The door stays open but when left alone Kenan and Kel go to look at it and it is now closed.
Answer: He's simply enjoying doing it himself. Especially since he likely believes he can do it better than she can.