But that doesn’t mean Michael Brown & Dorian Johnson knew that the officer didn’t know or wasn’t stopping them because of the robbery. They’d just committed a strong arm robbery & a police officer pulls up....
Of course they assumed the officer was there because of the crime they just committed. Hence Michael Brown’s aggression & resistance.
More importantly, the behavior Michael Brown exhibits at the convenience store fits with the behavior the cops describe at the shooting scene - he was physically aggressive, grabbing the store clerk by the shirt and shoving him backwards.