There are very few people who wouldn't consider being forced to move across continents, while giving up their rights, a highly biasing factor in the pros/cons of any decision they made.
PG's point is that a lot of people from outside the US (including from Europe) currently would prefer relocating to the US but they have difficulty getting a visa. Long term more and more people would prefer the second best choice that's available to them.
No, from my reading of pg's point: Most of the top programmers live outside of the US, so we should make it easier to get them by changing immigration policy.
This is a good point. But finding out that your employer is so nasty that they use your visa status as a bargaining chip, can be even more inconvenient.