User blog comment:Blur the Hedgehog/Why Isn't Metal Sonic in Sonic X?/@comment-1535286-20110610014341/@comment-17720060-20110610021852

Yeah, but remember, Archie made that Metal Sonic story. And the Sonic X series ended before the comic was even made. So Archie had the rights to make that story. Archie just fills in the gaps.