Without casting aspersions on Mr. Horn or his neighbors, I would expect the neighbors to be inclined to provide a narrative friendly to Mr. Horn regardless of what actually transpired. That is not to say I doubt Mr. Horn was, in fact, justified, but merely that I would not regard the neighbors' testimony as having overwhelming probative value. They're probably telling the truth, but it's not hard to imagine that they might possibly be shading things a little.
Indeed, and precisely what I meant by:
(regardless of any motive on their part, btw)
Probative or not, there is a certain value in their "shading" of things. If they are willing, that goes along way toward Mr Horn's credibility and their opinion that he is a "good joe". After all, if he were a problematic sort, prone to causing dangerous situations, I doubt his neighbors would "shade" anything.
Now, had there been injury to other than the obvious perpetrators, The DA may feel the need to be more probative. But considering the unified nod of the witnesses, if their testimony can be reconciled well to the audio tape, and to the evidence on the ground, I would be stunned to see the DA press the issue. This guy is close to hero material, and would make for a mighty unpopular DA.