I wonder if there is some middle ground here, between the fictional narrative of an execution killing, and thoroughly honourable citizens conducting a citizen's arrest..
It seems pretty obvious that he wasn't just guilty of 'being a black man on a jog', he was snooping and from his history probably up to no good, but also there weren't justifiable grounds to hold him via armed force, armed force which escalated severely when he didn't just stay still and wait for police (there's no evidence that they were planning to kill him, although he wasn't to know that I suppose).
I think people who bring weapons in to even a morally justifiable scenario need to realise that the outcome can be hugely problematic even if you 'win' (looking at you Kyle).