Several years ago DCL had a Galviston to San Juan repo, followed by a short cruise to Miami. We would have loved to take it but was pretty sure that it was not allowed. So we brought it up with the DCL person who said "No Problem" we said, "Check with a Supervisor" ... they did and came back and said, "You are correct, you cannot do that" so we didn't book either of those cruises.
#Sad
The PVSA has outlived its "usefulness" ... because the Cruise Lines really don't care about every registering in the USA except for the ONE Norwegian ship that sails around the Hawaiian Islands.