I think Thule is saying that all the hitch racks aren't ideal for carbon frames, since they all make some contact with the frame (at the fork, top tube, wherever). I have a Thule hitch rack (not the T2, but one of the top tube holders), and the rubber straps and cups keeps the paint in pretty good shape compared to most. Yeah, if salt or dirt is on your frame, the swirls in the clearcoat could be worse. It can also be hard to keep the bikes from rubbing on each other, especially with compact frames and varied handlebar widths. I'd maybe go with the T2 in the future just for ease of fitting different kinds of bikes and there's no need for a lot of extra steps like wheel straps.
I park in a garage, and so not having to worry about remembering when my bike is on my car outweighs any mild cosmetic blemishes that I get on the frame from a hitch rack.