I'm not surprised that an agent would shoot to kill anyone he deemed an immediate threat. In terms of firearms training, an FBI agent, just as a police officer, is not trained as a sharp-shooter, to try to disable or disarm a threat, but rather to aim and fire at the kill-zone, to eliminate the threat to his life or anyone else's on the spot, at that instant. If you grab a potato peeler and charge a police officer, she can and very likely will shoot to kill you. She will not squint, stare, do a double-take, try to discern if what you are holding is a lethal knife or a potato peeler. If you brandish it like a weapon, you will be treated as though you have a weapon. IT had a flip-out, violent history. He is strongly suspected of and ready to confess to a triple murder ( in addition to previous criminal conduct); he is connected to two known terrorists
and his body itself is a weapon. He grabs something it appears he might use as a weapon and he uses a table to slam an agent into the wall. That is all it takes folks. Protocol. At that moment, an officer of the law does have the right and the duty--and is trained--to act as judge, jury, and executioner. Most members of LE never want to draw their weapon and are very proud if in the lifespan of their career they have not had to. Once drawn, and it must be a split-second decision, either the threat extinguishes itself, and makes that clear to the officer, or it is extinguished. You can debate the practice/protocol, but it is one that's held to across the boards, so nothing unusual here in its application.