While I completely understand that sometimes human perception collides with sets of facts to create tragic mistakes, I can't think of a single instance where a non-LE got that same benefit of the doubt. Just saying.
And sometimes a use of force (by a cop or by a private citizen) will work out to be justified when the belief of a threat was reasonable, even if mistaken.
ETA: I just realized how far afield this this has gone. My apologies for contributing to the veer.
Also, I want to express my sympathy to Gray, who, for better or worse, has spent enormous energy, and time (and money, I presume) to attempt to further gun rights. Whatever disagreements some may have with the strategy, I do believe it was thoughtful and well-intended. And, for all we know, it may well be vindicated in the end. That is certainly my hope.