This continuous repetition of the St. Louis incident is one of the biggest red herrings of history. At the time the US was in the 10th year of a depression with 19% unemployment. The US policy for some time had been to limit immigration. There was no evidence Germany was going to institute death camps (the Wannsee Conference was three years in the future). To expect any country in those circumstances to open immigration is ridiculous. Hindsight is wonderfully accurate, but one must if interested in truth judge by the circumstances of the time an event occurred.
U.S. House Speaker Boehner brushes off call for his ouster (Reuters)
from the article: Study: Ben-Gurion changed his mind on Allied bombing of Auschwitz