If the guys arm was injured by the equipment the BG threw I would imagine it wasn't an eraser or paper clips. Sounds to me like a monitor or a printer or something similar. In that case that's felony throwing of a deadly missile which would be grounds for using deadly force.

Now if it was me, I wouldn't hesitate to use deadly force in my office. My office is a mile down the road from the county jail. All sorts of citizens who don't like to abide by the laws are walking by after they get released. We can be an easy target for a hold up to get keys to the many vehicles outside or money for drugs since they couldn't get their fix while in the hole.