BLM national org.: making friends with cops is bad, only hold them accountable!
Neither the people in Kansas nor BLM said anything about "making friends". And BLM never told those people not to go to the picnic. Anyone is free to go to a picnic with cops if they want. BLM said the event was not sanctioned by them. Any group can pick which events they choose to officially sanction.
Also there is a strategy called killing people with kindness. I think the strategy employed by the police in Kansas was a good one. It defuses the situation and makes them look like the people who took the high road. It is what I would have done if I was the police chief there. It's a lot more effective then being an antagonistic ahole. Now does that strategy address BLM's goals? No, not necessarily. It's totally fine for BLM to say they wish to pursue other strategies that will be more likely to achieve their goals. Optics suck but that's how gamesmanship works. And I'm sure there were tons of police officers who wanted to do the cookout not as a strategy but because they genuinely care about their community.
I mean if Hillary Clinton invited Trey Gowdy to a weenie roast I doubt he would go.