He's basically saying that a bad deal is better than no deal. Problem is, it's not even close to what you can call a deal. It's a non-binding political agreement between the UN P5 and Iran. Think about how silly that is. You've got the US trying to get assurances on nuclear weapons with the assistance of two fair weather friends (UK and France), two of our biggest geopolitical foes (Russia and China), and an openly hostile terror state (Iran). It'd be funny if the stakes weren't so high.