I don't think its too much of a stretch that brody was the only available person to handle the bomb maker. He was pretty close location wise and knew the guy, what else is needed?
Again, they reused the motivation from last week. Only Carrie can go to China. Only Brody can evacuate the tailor. They're like Starbuck and Apollo. The first time it was plausible, but the second time was not for the reasons I gave earlier. A Congressman is a pretty good asset, and to risk him on a field op, where anything can go wrong, and with the CIA closing in, really stretches credulity. That red-headed dude is pretty recognizable even if he does wear a baseball cap, and WTF is he doing running around with an Arab?
OTOH, Nazir must know Brody is compromised due to the video. Maybe they were going to kill them both out in the middle of nowhere, and Brody unwittingly saved his own ass. That must be it.
The whole killing scene definitely had some flaws but who cares.
When he hosed himself off at the car wash, I was thinking, "Damn, that's gotta sting." That was the high point of the misadventure for me.