First of all, I find it strange that you find no evidence of a firearm in his hand, that is apparent via the video evidence. It is apparent he has something in his hand that is very dark/black in color. Maybe a gun, maybe not, but every officer on the scene had a better view and they determined it was a gun. 

Second, A firing squad was not warranted? You do realize that one officer, a black detective, is the one who fired four shots and killed Mr. Scott? Not a firing squad.

Third, No demonstrated threat to personal safety of the officers or anyone else? Walking backwards with a loaded, fully cocked gun in his hand and ignoring more than 9 orders from the officers to drop the gun is not a demonstrated threat? In what way is that not threatening? Please think about it before you answer and demonstrate your lack of logic and common sense again.