I seem to recall during the SAS raid on the Iranian Embassey in Lndon years back one poor terrorist was shot by almost every SAS operative that went by him. He was already dead, proped against a wall, and doctrine dictated that you couldn't leave someone unneutralized in your rear.
Same principle. If you've got to move away from them, with the BG in your rear, make damned sure he's incaple of hurting you.
Battlefield situations are a bit different.