Are we sure it's even official?
It looks to be a case of "Yes, but...". The developer isn't Sonic Team or even Hardlight it's...Rovio Entertainment. It's a Sega company since they were bought out but it's the Angry Birds people. Some people are wondering if they jumped the gun on adding a few of these. Any character who isn't officially revealed can be denied as being in the game if Sega says no to their inclusion.