He answered the door holding the gun because the knock happened during hours when no reasonable person would be knocking on your door, and in addition to that they hid themselves to avoid identification after knocking. When he saw it was the police he immediately got on his knees and moved to put the gun on the ground. They killed him anyway. If that doesn't infuriate you you're hopelessly brainwashed. Police shouldn't be empowered to shoot whenever they see a gun regardless of whether someone is complying or not, and if they are empowered to do so then they have no one to blame but themselves when potential victims of police violence start shooting whenever we see police. They must want war in the streets because that's what policy like this creates.