None of those things should be a death sentence. A guy who tells the cop he has a gun is not a threat. The cop screwed up, he’s a trigger happy moron. The jury screwed up, they got snowed by the usual “cops are awesome” BS. Period. This was murder, and he got away with it.
It’s tragic that Castile was killed, but I’ll go with the jury over your indictment for murder since they certainly had a wider and more thorough view of the case than either you or me.
Even the prosecutor wasn’t going for a murder conviction, by the way. He was tried for felony manslaughter, a lesser offense.
As for your assertion that “a guy who tells a cop he has a gun is not a threat,” I’m betting most law officers would disagree with you on that one, though I could be wrong.