The only sports cars I saw in that comparison were the Z, Porsche, and BRZ.
Like you all have said, the others are just "sporty" cars (aside from the TC).
Seats/Drivetrain/etc. don't warrant a sports car - I define it as built with intention for driving, not for being a people mover.
However I do feel RWD, 2 seater coupes are generally the purest defintion. And 911 backseats aren't real, children have a hard time fitting in there. I think they only do it for insurance purposes which is brilliant, as a 4 seater generally insures for less - thank you Porsche!