Sorry I didn't see your post until now. And it was the cruise director, I believe, who said that about their crime. Riding around on the tour, I have to say that we saw a lot of extreme poverty, graffitti, vandalism, etc., which led me to believe that it was the truth. I had wanted to see the interior of the island so had already chosen a ship's tour anyway.
I'm finding it hard to believe that St. Thomas is high crime. Have been there on cruises and to stay in a bed and breakfast and never saw anything that put me on high alert. Nor did I ever hear anything about crime. Maybe the ship wants you to buy their rum, instead?