I agree with your assessment that it was the right call because at the time it seemed like he had deliberately set up his own capture. So with that being said, was it really all that out of character for Ward to kill him? Ward kills people all the time when they are an immediate threat and there is no other options. He's a tactical guy, it's his job, it's what he's trained to do. Considering letting him go wasn't an option and the situation seemed to indicate that taking him into custody was just part of his plan, is this really that different?