The article says they negotiated with him for 10-15mins but he did not drop the knife. And still he advanced towards them with a knife after that long.
10-15 mins is plenty of time to drop a knife. There is no reason to start moving towards the police holding a knife, after they talk to you for so long.
It seems to me -based on the fact that he tried to commit suicide in the past- that he wanted to die. And by doing this type of suicide, his family will get money at same time from suing the police. This is called suicide by cops.
I may be wrong though and the person may have had serious mental health issues (which would still make him a threat)