Gotcha I didn't read down far enough.
I thought they did away with this? see below in orange
Except where it is a mandatory requirement, Carnival highly recommends that all guests travel with a passport. The passport must be valid for at least six months after the last day of the cruise. This will enhance the debarkation experience as delays may be expected upon return to the United States for those without one. Additionally, this will enable guests to fly from the United States to meet their ship at a foreign port should they miss their scheduled port of embarkation and allow guests who must disembark the ship before their cruise ends, due to an emergency, to fly back to the United States without significant delays and complications.
U.S. Domestic Cruises
For cruises that begin and end in the same U.S port, the following WHTI-compliant documents are acceptable for cruise travel. Please note that if the cruise visits Colombia or Greenland, a passport (valid for six months after the cruise ends) is required.