When faced with a situation of uncertainty, one can choose to escalate or de-escalate. Not having all the facts, it's impossible to know with certainty, but it appears to me that the officers in this case rapidly escalated the stress levels and turned what might have otherwise been a simple conversation into an arrest.
So, you think the officer should have reacted to this call to de-escalate the situation? You think the officer escalated it by asking him to disarm and then when he refused it was wrong for the officer to resort to drawing his sidearm to get the suspect to comply?
How is the officer supposed to determine an armed person is NOT a threat? We aren't talking about an officer driving by and seeing someone armed. We are talking about an officer responding to a 911 call about an armed person. Your 'simple conversation' cannot be used in all situations of uncertainty.