There’s no basis to this claim at all lmaoAll that would mean is that Green Hill, Chemical Plant, etc. are also illusions. It doesn't disprove illusory Stardust Speedway in the slightest.
these are just two different possibilities that happens after Egg Reverie Zone: Sonic gets sent back to Angel Island and starts Mania Plus or Sonic gets sent to the Modern Timeline, where he’s featured in Forces and comes back for Mania Adventures. There is way too much evidence that goes against your argumentOn that note, it could also be that Sonic was sent directly to Encore mode, and the Classic Sonic that appears in Forces is actually an illusion created by the Ruby at Egg Reverie that was sent into Modern Sonic's timeline by the Emeralds. This doesn't need to be true as it doesn't really change anything, I just wanted to point it out as a neat possibility.