Nanoterrorism is going to be a bitch.
If all research is confined to individual companies working independently, without collaboration across (taxpayer-funded) academia, it will slow things down considerably.
Let me ask you this: What do you think would happen to the quantity of output of various types of literature and art if copyright protection was taken away? Do you really suppose it would be any different with patent protection?
Eliminate progress in the US, and you push it toward less responsible regimes and cultures.
If another culture comes up with a technological advance, there's nothing stopping us from making use of it as well, except our own insane willingness to agree to treaties that prohibit that. We put ourselves in greater danger from irresponsible use of this technology by continuing with the mad rush toward making it cheaper and more powerful, than we would by adopting policies that slow down our contributions to it.