In the end, a citizen was killed by the police in the privacy of his own home.
That said, without more information I have to concede that the police were in a no-win situation. If it was just a welfare check -- he was up, mobile, and [somewhat] lucid. He asked them to go away, and they didn't. If I were in that situation (as a homeowner), I'd be upset, too.
If he had been making threats, that changes the situation considerably. If they had gone away without doing anything and he then proceeded to shoot or kill someone, they (the cops) would be criticized for not having prevented the shooting.
My summary is that two wrongs don't make a right, and in this case both sides acted idiotically.