I've commented on retconning and changing Greg's height several times before. To recap: He was super tall and I kept making him shorter to better fit him in panels the end.
The thought process behind this EGS:NP, however, was as follows:
I've gotta write the next EGS:NP, but I don't want to keep doing gaming related comics in EGS:NP, and I'm not ready to do another storyline. Think of something think of something think of something GREG'S CHANGED HEIGHT OVER TIME DRAW GREG ALSO DEX VICTORY IS MINE
Writing is a delicate and highly intellectual process.