And I don't. I agree that the public safety exception may not apply, so any answers he gave might not be able to be used against him. That doesn't mean that he's off the hook for the death penalty, however. One doesn't need a criminal's own testimony to establish mens rea. I think there's an overwhelming amount of evidence to establish that he had intentions toward committing a terrorist act.
Dershowitz is a great lawyer, but he's also very liberal, and I think his bias is getting in the way here.