State of mind is a factor.
When told to leave the middle of the street and move to the sidewalk, Michael Brown swore at the officer.
When Wilson tried to exit his police vehicle, Brown pushed the door in, pushing Wilson back inside.
Those two acts alone establish that Michael Brown was not in a law abiding, gentle giant mode.
Grabbing the officer’s weapon was strike three.
Not to mention he had just robbed a store and assaulted the clerk just before this happened.