Or a similar event- this past spring my sister and her husband caught the Cunard line's Queen in LA, berthed in Hawaii, picked up more passengers*and then onto 4non US*stops before getting off in Sidney and flying back to the US. Lots of "exceptions."
Those are not "exceptions", the*ship*did not*load passengers in LA and offload them in Hawaii so they did not*tranport passengers or cargo*between US*ports.
It is perfectly legitimate to pick up pax or cargo at several US ports, or to drop off cargo that was loaded overseas in several US ports. The point is that a foreign flag vessel or a foreign bottom cannt pickup pax or cargo in one US port and drop it off in another without first stopping at a foreign port. Foreign cargo ships commonly offload part of their cargo in Long Beach then continue to Oakland to offload the remainder. They just can't pick up LA cargo and drop it off in Oakland.
The cruise ships working out of LA skirt this by stopping in Ensenda for a few minutes on the way to Hawaii. That practice has been determined by the government to be an "evasion" and may soon be stopped. The ships may have to stay in a foreign port for something like half the total time they spend in ports.