A local fellow (N TX area) recently passed on. He had been a professional criminal, who burgled to support his drug habit. When chased by police, he had found that he could get them to take cover by "drawing" an imaginary gun, and doing a fair impression of a Weaver stance with his finger-pistol, made up of two fingers stuck out at the officer. On a couple of occasions this had worked, so he just kept it as part of his repertoire. On about the third time he tried it, the officer knocked him down and took him to jail. On about the 4th or 5th time he tried it, the officer involved (each time it was a different cop) responded by appropriately shooting him in the head.
Surprisingly, he recovered with about 1/3 of his brain intact, and spent the rest of his daze in a wheelchair, smoking and drooling. His family had attempted to sue on the grounds of "police brutality," but after the third officer testified to his manual habit of intimidation, the finding was for the department and the officer.
A threat of deadly force is just that. Lack of a real gun makes no difference, if the perceived threat was there.