If somebody gets shot by the police because of having a gun like taser than, well, it´s exactly the right time to talk about gun culture and gun control.
In this case, it's worth remembering that the victim was reported, in a 911 call, to have been carrying a pistol. Not a taser. The police came to the park to confront an armed subject. Upon finding him, they told him to show his hands. He refused, and then pulled out his weapon.
The police would have had just moments to decide what to do. You can imagine the level of adrenaline they were dealing with was such that they could probably taste it.
The police obviously made the wrong decision. But they were set up, by circumstances and by a system that forces police to make split-second life-or-death decisions like this routinely.
...and set up by military and paramilitary training to treat any potential threat as an actual, lethal threat. Furthered by the knowledge that the alleged aggressor was likely of an undesirable economic group and race.