That's an interesting observation. In my younger days, I worked in university security. The university was located in a big city. I had a lot of interaction with the city beat cops. Most of them were older men, veterans of WW II.
And I believe that they would have all behaved as poster FBD would have. If Garner wasn't doing anything grossly wrong at that moment, they would have just said hello, and left it at that.
Something certainly has changed here.
Brother I worked with cops from that era. They were the same as cops today, there were good ones and bad ones. Everybody and their brother didn’t have a video camera rolling back then. Some of them told me the stories of what they did themselves. The story of the nice old street cop back in the day may sound nostalgic but I know better.
People are people since the first day.