Flying Guy
Do you seriously believe that charterers carry out a security screen of someone who turns up to hire a light a/c? They'll check the guys licence and medical and recency and take him for a check ride. Any one of the 911 terrorists could have got through that, and indeed did. So unless things have changed post 911 and they are now enforced to security vet people first the same simplicity of hiring a light a/c in the US will remain. In that light, the decision to stop foreign registered light a/c is not alone going to solve that problem.
PP