His wife was still on board, in fact she went back to get a bag. She had already informed the marshals that her husband was sick. And after being shot Alpizar wasn't much good at id'ing bags; was he? Do you really think that it is an appropriate policy to shoot passengers who get off the plane because the baggage would have to be rechecked? I don't think you do.
And I have no idea what "three major risk factors each of which indicates a high risk" you are talking about; or how that justifies shooting an unarmed man who has already left an airplane.
What assumption do you think is proper to be made when a passenger disembarks leaving his checked bags and whatever else he may have left and refuses to be stopped by authorities?