I really want to believe this, but I'm not sure that I do.
Of course the tech companies want to hire people from overseas; being able to hire someone from India for half the cost but have them live in the US so there's some level of accountability/trust is a no-brainer. Huge new, cheap talent pool.
But, if I'm an entry-level, US-based programmer, what I see are floods of cheap talent, some with questionable skills, coming over to compete for my job.
On the surface it seems as simple as a conflict of interest between employees and the companies that employ them. Supply/demand.
Dig a little deeper and the argument becomes that the top programmers we're bringing over are going to start great companies. That makes sense; part of the reason the United States is so powerful is selection bias: If we create an environment the hardest-working and smartest people in the world want to come to, the end result is a lot of great companies that create enough jobs for everyone. Elon Musk isn't starting Tesla or SpaceX in South Africa (where he's from). So we create an all-star selection of the human race in one country, make laws that are favorable to people coming/staying, and the economy explodes.
What I'm not clear on is what the effect of opening the doors to programmers would be. Would truly great companies be started enough that the entire economy is shored up, or would it just dilute the talent pool to the extent that being a programmer isn't a "special" job you get paid $150,000/year for being decent at? The long-term, macro result of this would be interesting.