My assessment is that (in that photo, MediaMole) those several standing immediately by the President as he approaches the fray are not USSS, but rather, Chilean protection service amd[protocol types. Further, if the USSS were standing next to him, I am sure they may have blocked the President from getting into the fray. He's walking over pretty much on his own here.
I agree. And you can see, NOBODY has their eyes trained on the President.