I found the Thiel-Gilder debate.

Thiel's list of fields where "innovation in stuff was 'outlawed'":

• petroleum engineering
• nuclear engineering
• electrical engineering
• chemical engineering
• mechanical engineering
• bio-engineering

I can believe that changes in the law and the legal-political climate have hampered innovation in at least some of those fields, but by "outlawed" Thiel seems to mean "a bad career choice", judging from what he says at 42:17.

Edit: Thiel does not just mean "a bad career choice"; he gives some examples of what he does mean at about 9:50 of this July 16 2012 debate with Eric Schmidt:

I think it's because the government has outlawed technology. We're not allowed to develop new drugs with the FDA charging $1.3 billion per new drug. You're not allowed to fly supersonic jets, because they're too noisy. You're not allowed to build nuclear power plants, say nothing of fusion, or thorium, or any of these other new technologies that might really work. So, I think we've basically outlawed everything having to do with the world of stuff, and the only thing you're allowed to do is in the world of bits. And that's why we've had a lot of progress in computers and finance. Those were the two areas where there was enormous innovation in the last 40 years. It looks like finance is in the process of getting outlawed, so the only thing left at this point will be computers [...]