User blog comment:MeltingMan234/List of Banned Characters in the comic/@comment-6576725-20131026035631/@comment-457038-20141210142949

It's probably legally sensible.

I think it's because in the games it's hard to tell if it takes place on another planet or another version of a future Earth. They haven't named it in YEARS. After all, Archie's Sonic Universe is SO different from Sonic Team's version. They probably just don't want any copyrite battles over the word 'Mobius' with people saying things like "Well, Sonic's so different and it takes place on a different planet; Sonic now belongs to us, better get out your wallet and pay the royalties."

Archie isn't a little business. It's one of the big guys, just like Sonic Team. We really don't want them going toe-to-toe.

If Sonic Team decides to name the world Sonic games take place on, then maybe this will be solved.