The CIA said that to Brody, so he went along with it. He did pull the vest and it did not work and then went to the bathroom to fix it. Brody is so messed up. Because he was swayed by Abu Nazir, it must be easy to sway him back - he is in survival mode? Going along with what is in front of him? Lewis is just amazing conveying what is going on with Brody. And the continuation of the affair as a cover is very useful. Now in hindsight the affair really fits into the story much more than before. Me too - shows like this are much better watching episodes back to back! But I have no patience!!!