I believe Zim was shitcanned after the 9/11 Attacks. Because, you know, people never thought of invading America before and the cartoon could cause little Johnny and Deborah to go completely apeshit, start wearing turbans, and start cutting Achilles tendons when they were asleep.
About fucking time, I'd say. One of the best reasons to watch Nick before everything because a stinking sack of rotten baby food. I still miss Kenan and Kel.