An Amel owner just asked me if boats were still allowed to go to Sint Maarten, so I went to Immigration and ask.  

Only incoming “commercial” flights from the US, UK and EU are canceled as well as cruise ship.  

Private jets & boats are still allowed to come to the island, “REGARDLESS” of where they are coming from. 

Which is not the case for Turks & Caicos as a friend of mine (non-Amel owner) was denied access since he came from Dominican Republic.  

Hope that helps.