How does it stand incorrect? My statement was that Skinsuits are road cycling attire, TT is categorised as road cycling by the UCI, so skinsuits are road cycling attire. Just because something exists in a subcategory doesn't make it not part of the parent category.
Time trials fall under road cycling by the UCI, and skinsuits are most definitely not banned for them. For the wetter areas of the world, dirtsuits are onesies for mountain biking to shield you from...dirt.
Its not a skinsuit, just because they list one piece clothing separately doesn't mean that a skinsuit isn't one piece also, things can fit in multiple categories at a time, Skinsuit = Road bike clothing, Skinsuit & One piece clothing. The seperate mention of one piece clothing here is included for things like dirtsuits.