This is the equivalent city scenario prior to this time. You are at a ball game. You arrive to find someone sitting in your seat. Not a huge scary someone. Just a regular someone.
Would you call the cops? No.
If you did, would they respond? No.
Would there be any sort of internal investigation later? No.
Why? Because until the moment the guy in your seat starts pumping bullets into you and everyone around you there is no reason to take that leap.
Outside of a few neighborhoods people don't get shot because they ask someone to move. They just don't. There was no reason to believe that this time would be any different. All of this is Monday morning quarterbacking to the extreme.