In my opinion, he made three mistakes:
1. Talking.
2. Opening the door.
3. Holding a loaded gun in his hand when he answered the door.
https://www.msn.com/en-us/news/crime/family-of-air-force-airman-23-fatally-shot-by-florida-sheriffs-deputy-demands-release-of-bodycam-video/ar-BB1m6UBd?ocid=BingNewsSerp
Little Rock, Arkansas Police carried out over 110 NO KNOCK warrants last year. They place explosives on the door frame to your house at 4:00 AM under cover of darkness, then blow your front door right off the hinges. While this is going on, your neighbors are out front recording all of the action on their smart phones for a fast upload to face book.
Then 100 SWAT team members come blasting into your home, guns fully loaded. Wrong address?? They obviously do not care. And to think you thought you were being burglarized......