How can you protect someone if you don't know where they are?
How much time does an offensive line (American football) spend looking at the Quarterback? None. The lineman work with their back to the Qback.
Look at the many pictures on Daily Dose the last four years that have an SS agent visible. How often do you see the SS agent looking at the President - none. How often at the crowd or possible source of a theat - always.
Though, for another reason, I will change my position, taken earlier on this thread, that the wall of security types in suits that W. reached over are American Secret Service. Instead, I take it now that they are Chilean security. If they were our SS, they would have let the trapped agent through, without hesitation.
Someone above noted that the problem started when they let W. out of the limo in the middle of that crowd, with just a couple of rope lines holding the mob back a few feet. They should have taken stock of the situation, and drove on. I agree.
And the Chilean security, having just seen W. and his security form a bubble of protection around him and the Limo surely must have known that the man they were blocking was coming off the tail of that bubble. What in tarnation were they thinking by blocking him?