The guy got killed for making a mistake, being honest about prior interactions with police, and taking medication.
I agree, that why it is sad. However, to determine whether the actions of the cop where justified this, like much of other things mentioned, is hindsight bias as well as some preconceived notions of who the villain and victim is.
Honest shmonest as far as the cop knew, he had a middle-aged man in the middle-school's parking lot during kids pickup. Who reportedly was trying to get into multiple cars, became 'aggressive' and was possible 'on something'. The person didn't look too healthy, behave nervously, admitted previous altercations with police, admitted screaming at someone all which substantiate parts of the previous report and would give anyone with common sense a reason for caution at least until more facts can be established about the situation to corroborate different stories. Unfortunately things escalated before even basic identification could be made.
So the whole story is about (1) the split second decision to take control of the situation when the suspect turned away doing something sneaky in the car, with above context in mind; (2) whether the shooting was justified during the struggle that ensued. Note that the cop end up on the floor, seem to be under the suspect for a second, and reportedly hit in the face (for anyone who never been in a fight, that can be disorienting) and felt that the suspect might be reaching for his gun.
Again, I don't know about the answer or whether my impression is correct or based complete facts, but I do know that on politically polarizing issues people often don't care who get thrown under the bus