I disagree with your assessment of the arrest.
The victim was grabbed and pushed outside because he was trespassing. He was told he was under arrest. He was forced against the wall, perhaps unnecessarily, perhaps necessarily. Being under arrest, he can legally be subjected to a forcible takedown. Although the victim had a license to carry concealed, if under arrest, the weapon cannot legally be utilized in any way. The cops were blatantly identified as cops, did announce the victim's arrest, and at that point the gun should not have been drawn. In the physical struggle, when the victim pulled the weapon, it justified the first as well as the second (lethal) shot by the cop. The first shot was an error due to it being placed incorrectly. It should have been the lethal one. Under the circumstances of the rapid motions, it is understandable, though still an error. But that is a matter for the cop's training.
Events surrounding the arrest and shooting are irrelevant.