I have a few thoughts:
1. Mr. Graham can drop dead. I had to look up who this guy is, Y Combinator has produced such companies as:
Scribd, reddit, Airbnb, Dropbox, Disqus, Stripe
These are not the companies that make the US a "tech superpower". We have a document sharing company, an online community that is 33% porn, 33% cats, and 33% reposts, a house-sharing operation that is constantly on the run from regulators, a company that resells cloud storage to end users, a company that facilitates cat-posts online, and a credit card payment processor. News flash, the world let alone the United States does not revolve around Silicon Valley and your narrow alleged needs. This guy is crazy if he thinks we are going to screw with the iron clad law of supply-and-demand and let in a "few thousand programmers" for no good reason.
2. Mr. Graham knows that he can already get in the very best programmers. We have plenty of avenues for letting in the very best. For one, it means, we have a real shortage. Secondly, it might mean we educate them here. Finally, it may mean you have to really invest in attracting the top talent internationally. That may mean - gasp - setting up foreign operations, and then domesticating the worker after a few years. That's right, Mr. Graham, years. What he really means is "we want to attract the best programmers, for cheap, chain them to a job, and then wash our hands of them when the job dries up or it doesn't work out".
3. This is yet another case of an over-privileged idiot trying to social costs and privatize profits.
4. The reason you can't find as many American top programmers to work for you is because Silicon Valley sucks. The culture sucks, the location (esp. real estate) sucks, the working environment sucks, the stability sucks. It's just another gold rush scenario, this time with Aeron chairs and floor to ceiling whiteboards, and lots of fast talk. And let's be honest. The work sucks. Most of these starts up are doing nothing at all really useful. A huge majority will fail, suddenly, having wasted everyone's time and someone poor suckers money. Spinning this as disruptive, or revolutionary is sad, and a lot of people are jaded against it. The company structure sucks. There are many programmers who have been to three, four, five failed startup operations, going through the same stress, the same pain, the same loss only to end up being told they are now too old for another try at the pie. There are no plans to provide for a long-term company, no hope for a business that is lasting and built upon solving problems that people are willing to pay to have solved.
5. The fact that Mr. Graham and his friends can't attract a few thousand of the best of the best to work for them just means that the costs outweigh the rewards. Instead of fixing their toxic culture, failing mentality, and gold rush dynamic, they want to break the country further. Because they feel entitled to have what they want, without putting in the years, or decades that other industries have to make it to stability. They've already been given a subsidized work force, where they feel entitled to reap the top talent for middling pay, massive cultural influence, outsized political influence, and regulatory preferences. And yet, they've done almost nothing for the country. We are plus 10 new billionaires, but there has been no standard of living bump for most Americans.
TLDR: Drop dead, Mr. Graham. You do something for the country, and the rest of flyover territory will think about doing something for you.