It is actually almost certain that it is just a white lie that Mark the Tapir from Sonic Boom Season 2 is not based on Chris, right....? I mean, even if Cartoon Network themselves announced at least publicly that Mark the Tapir is just based on general behaviors of obsessive Sonic fans, I suppose that it is actually quite clear to everyone that the animators were heavily inspired by Chris when creating this "obsessive Sonic fan" character.
Basically, if they were really just going for "general obsessive fans," the character does not have to be depicted as showing autistic symptoms, but Mark the Tapir does show several autistic behaviors in that short 11-minutes episode. If Mark the Tapir is "not based on Chris" just as it was publicly announced, then why adding those autistic stuffs along with the obsessive fan behaviors?