But it no more entitles the property occupier to shoot the miscreant in
the back.

Not as a "matter of right" but the circumstances could be that the "property
occupier" has reasonable fear that the "miscreant" still represents a threat
despite having his back turned.

Seems to me that the "boys" started it. They initiated the confrontation.
The "property occupier" should not be expected to operate with 20/20
hindsight.

--
Colin Rosenstiel