Hello!
I could be wrong, but I believe these measurements are for cruises in the Caribbean and Bahamas only (https://www.msccruisesusa.com/health-and-safety-measures/caribbean-cruises). For other locations, testing may still be required, considering that it is what appears on the Grand Voyages page (https://www.msccruisesusa.com/health-and-safety-measures/grand-voyages-msc-world-cruise).
On the main health & safety measures page (https://www.msccruisesusa.com/health-and-safety-measures) it states that "Vaccination and pre-cruise testing are recommended, but not required, on most cruises". That is, on some cruises, vaccination or testing will still be required.
I believe this can cause confusion for passengers.