The C8 is a dual clutch not an automatic. Which is a manual trans with an electronically controlled clutch.
Exactly why is it not a Corvette? If you want to get technical any Corvette with a V8 and not a Blue Flame six is not a real Corvette using this logic. I think Chevy decides what is and is not a Corvette. It still Americas sports car which seems to be the main requirement to be a Corvette. It sure looks like a Corvette.