And that right there is the point of contention. Ersland says the perp was continuing to be a threat. Prosecutor says not. Video is inconclusive (it doesn't show the perp). Ersland was there, Prosecutor was not.
Who ya gonna believe?
From the video it looks bad for the guy speficically for the time it took him to get the second weapon. That shows coherent thought. and that, in the law, is murder.
It doesn’t really matter who you believe. The man (pharmacist) is innocent until proven guilty. I don’t see much more than a speculative case here.