1) There'd be more great programmers if they wouldn't all divide themselves amongst so many startups, the vast majority of which will fail. Some other VC's have pointed out this problem as well. Less start-ups overall would increase the amount of great programmers available, and maybe more of them would succeed.
2) PG himself has said that great programmers grew up coding. PG's own population argument misses this as the greatest populations (India / China) do not have the wealth for kids to grow up coding. As people trying to increase the diversity of programmers have pointed out, getting this type of upbringing is hard even in America if you're not a well-off (generally white) male.
There's plenty of talent here in America, but let's be honest, its harder to utilize. It's much much easier to just import talent from countries that have education systems and cultures that do better at creating programmer talent than to fix America's deficiencies.