The Jews in Egypt were not immigrants, they were slaves. If the author of that story knew anything about the Bible, he would have known that Moses had to force Pharoah to let his people go, by bringing the 7 plagues on Egypt. Even then, Pharoah changed his mind after first letting them go and pusued them with his army.

It's amazing how people who aren't even Christian will attempt to use the Bible to make their arguements.