How would the cops know he had dementia? Unless the caller told the dispatcher they would have no way to know this. Only a call of a man with a gun and a man walking toward them who will not follow commands and take the hand out of his pocket. This was a tragic accident. The only fault with the cops I might have is 7 rds. fired to stop the man, why so many?
Then again, maybe they do. After all, what's the life of a citizen when compared to one of the protected class, who might piss his pants if he were faced with someone who actually was a threat. I'm sure the 73-year old man was a frightening specter to behold.