Is embargoing the foreign workers, who are perfectly willing (an understatement in many cases) to work for the wages being offered, ethical? I would say no.
I personally feel that free trade is far more ethical than nationalist isolation/protectionism. (It's not just Americans that are "entitled" to a high standard of living.)
The foreign workers are probably elevated much more (in comparison to their peers) because of their job than their counterparts here in the US are, but exploiting this difference in living wage is not ethical in the least.