I think that's a reasoned approach, and I'm happy to share my philosophy on that, as it's definitely relevant to how I've been moderating.
If you want to take another user to task for their behaviour, I don't think there's an easy way to do that "in public" without (even inadvertantly) encouraging brigading (or at least, to the user, the potential perception of such). You are better off talking to them in PM. Like at a party, pull them aside and tell them they're drunk and need to tone it down, don't call them out in front of everyone sort of thing.
If instead of just taking issue with their behaviour, you believe someone is acting in bad faith, PM me instead and I'll address it. I don't think either of those belong in the original topic because they will, in the end, almost certainly lead to a derail.
If instead you disagree with the position someone has taken (instead of the person themselves), and it happens to be tangental to the conversation, then by all means - spin off the topic (or PM me to, but seriously, you can all do it, too!), and discuss away. We mutants tend to be lateral thinkers, and I think you'll find that discussions split off in all sorts of crazy ways as a result of some of what we cover here, and many of those topics deserve their own, dedicated posts themselves.
I hope that's both a) clear, and b) reasonably sane policy.