I'm sure you're aware there are many countries with travel restrictions throughout the world. The Pacific (the French colonies of New Caledonia and French Polynesia not withstanding) are almost certainly ill equipped to handle a serious health outbreak.
Many of these places represent the developing rather than the developed world in terms of health care systems.
However, even if it includes crew these medical certificates are unlikely to be worth the paper that they're written on...
Also, I doubt there are many passengers in transit through PPT.