Although Jimmy just dropped a load equal to that of an elephant's, he dropped a load nonetheless. A normal one, normal semen that did not turn into a cannon ball as soon as it headed for the outside world.
Jimmy was happy that he could make this happen. Shooting out cannon balls was fun, but he knew that he couldn't have fun forever. A harem of primal beauties wasn't going to have sex with him forever just for the fun of it, and simply said, his girlfriends would want children sooner or later. He was aware of that fact, so he was happy that he technically could impregnate them now.
With the right 'buttons' pushed, his semen wasn't a danger to the world anymore. He turned the cannon balls off, and he felt confident that he could turn them on again. Deadly cannon balls seemed to be the base version of how his magic currently worked, so yes, he could easily switch back to it.
