As I said, the small number of cars involved do not make this an overall traffic volume problem. The Gowanus, BQE, bridges and tunnels are already a mess. The added traffic will make no difference on these routes, but these few cars have a multiplying effect at the tip of Manhattan.
The problem will get worse in the next few years, as tour buses start visiting the WTC, and construction begins on whatever is decided for West St and the East River waterfront.
This is planning in the wrong direction, and the city paid more money for it. They could have purchased smaller boats.