The US State Department has just aligned its travel advisory levels with those of the CDC for international travel. Over 80% of countries are currently rated at level 4, including Canada, Mexico, and all of Europe, due to the pandemic. If the CDC and State Department used the same criteria for domestic travel within the USA, virtually every state would also be classified as a level 4 travel advisory.

The island, in terms of cases, is actually one of the safer destinations in the world right now, despite the advisory. For the record, it is only the French side (St Martin) that is rated at level 4, the Dutch side (Sint Maarten) is actually a level 3 advisory. So you should not feel any less safe than you would at home.