I will ask you the same question I posed to others. If you see a cop assaulting a citizen will you step in with your firearm? Or step in period? Be Honest?
I'm afraid you're asking a bit of a red-herring question. In the first case, when a cop is seen using force there is some chance the force is justified or required to stop unlawful conduct or effect a lawful arrest. Such questions are less likely to be valid when a person is engaged in armed robbery at a restaurant or convenience store.
But put another way, the effective question you're asking is, "If you see a gang of 100 well armed men beating someone are you willing to step in on the same basis as if you see 1 lone assailant beating a person." When you take on a cop--no matter how well justified--there is a very good chance that sooner or later you get to take on the entire rest of the thin blue line, plus prosecutors, judges, and then prison guards. In short, a cop represents the power and authority of the state and in most cases will have that full power behind him.
Take on the one criminal dirt bag and a half dozen cops show up to assist or finish the job of ending the threat from the criminal.
Take on one cop, and a 4 dozen of his buddies show up to end the threat against him.
Those are two very different equations and I can't fault anyone who has a different response to those two very different sets of circumstances. Jumping into a swimming pool to save a drowning child is a prudent thing for most anyone who can swim at all. Jumping off a boat, into high seas may well be sure suicide even for the strongest of swimmers.
I simply don't see that your question--or most answers to it--provide any real benefit to the discussion.
You've asserted that this was "just an armed robbery" and thus didn't present much risk to life or limb. I and others seem to think that is a bit of an unsupportable statement. Your question about confronting cops looks a bit like a dodge to avoid answering how you'd respond to an armed robbery against yourself or a family member. Clearly an armed robbery is a threat to life and limb and most anyone might be expected to respond with deadly force.
There remain legitimate questions about the prudence of intervening in behalf of others. But I don't think claims that armed robbery is not a real threat to life or limb are the way to approach that. It seems the situation was less exigent than an active shooter situation. But if one is going to act, it seems waiting until the criminal forces victims into the freezer might not be the best course to follow either.
Charles