Perhaps a disgraced and embarrassed ex-cop father who had visions of personal redemption dancing in his head for many months (hero with LE cred saves the neighborhood from scary UBM burglar!).
((I was struck by Agent Dial saying he believed GM probably WAS thinking "don't shoot, Travis!," but just didn't say that out loud, even if he thought he had.
At first that seemed like an extremely generous take on what might have been going through GM's mind just before and during that first shot by TM into Ahmaud's chest. But.....maybe not. See above)).
I think you scenario is plausible.
The GBI struck me as being consulate professionals. If GBI agent states that he thought GM had wanted to call off the confrontation short of shooting the victim, I can accept it.
A possible thought by GM of calling off the confrontation would also coincide with his police experience (even if less than stellar).
GM's police experience may have led to a quite voice telling him that corralling and bringing in the 'perp" (no doubt in his mind to the expected accolades of the neighbors put into what, legendary epic poetry and song?) would be acceptable legally. But... actually shooting AA was entering into unknown territory.
Too bad that GM ignored the voice. He could have called loudly to TM to "Let him go!!" as soon as he exited the truck with the shotgun. In all probability, AA would have then not defended himself, but continued to flee.