You would have the opportunity to completley disarm the threat right then and there, and I don't think I would be able to sleep at night if I failed to act, and someone else got shot as a result when I knew I could probably have quickly resolved the issue
And again we see the problem with this sort of stuff. First, the assumption is that the GG will win without any trouble. What happens when you try to disarm the threat, and you miss, or lightly wound him? Or when his partner, who you hven't noticed before, pulls out his gun and now starts shooting? Can you sleep at night if you do act, knowing that your actions started a gunfight where someone else got shot? How does one reconcile "I could probably have quickly resolved the issue" with "I failed to resolve the issue and instead made it worse"?
Folks, there is a reason that EVERY professional security agency, LE agency, and everybody else involved in this sort of stuff recommends against intervention/resistance except as an absolute last resort.