King, you are ignoring the fact that IF Tamir was reaching for the gun, the police don't have the luxury of waiting more than two seconds. In my first post on this topic, I mentioned that a police officer was shot and killed while making a "routine" traffic stop. The scumbag shot and killed the police officer in less than two seconds. If I'm a police officer and someone with what appears to be a real gun reaches for that gun, I'm shooting him regardless of whether ONLY two seconds have expired since I arrived. If police officers hesitate or wait, they die.
The age of Tamir doesn't matter either because there have been a number of 12, 14 and 16 year old individuals who have shot and killed people. If the child is old enough to hold a gun, aim it, and pull the trigger, then they are old enough to shoot and kill and must be treated with the same as a 18 or 20 year old who is brandishing a gun.