The world of Sporkman has changed since the last comics were posted in 2008. In the intervening three-odd years, our hero somehow shrank: whenever I draw him in different art styles (in Lit Brick or Silver Age Sporkman, for example), he stays chibi while everyone else is their average adult human height (five to six feet). This is largely because Sporkman just looks weird if he's not short and vaguely adorable.
This change is being carried over to Classic Sporkman in a slightly more subtle way. In most of the newer strips, he's drawn just a few inches shorter than everyone else, or drawn closer to the camera to balance things out. I'm basically just fudging his height unless his shortness is required for a joke, as in today's strip.