I’m responding to your queries before coffee, so please allow for that.
My interpretation of the rules: An OP has some control over how a thread progresses. In the past, if a poster has included language in their OP that they don’t mind some hijacks in their thread, we’ve generally respected that to a point. @What_Exit clarifies that we still won’t permit omnibus threads.
He also indicates that the OP does not own their thread, and they don’t. We have final say over how to moderate any thread. Nonetheless, I agree with his point that the more detail included in an OP, the more guidance we have for keeping it on track as the OP wishes. And an OP can always flag deviations in their own thread if they feel the thread is going off the rails. We will usually accede to their wishes – though not always.
In this case, the moderation was in response to a thrown flag. My review of the OP did not indicate that discussion regarding where polling places are located had anything to do with a Macomb, IL election judge being removed from office, and I agreed with the poster who threw the flag.
When the OP ignored the moderation and responded to the hijacks, my feeling was that if she didn’t care, I wasn’t going to, either. I might have felt differently in another circumstance. Still, it troubled me and I don’t appreciate any poster just ignoring moderator instructions, even in their own thread.
To me, it’s not about how active a thread is or isn’t, or if a hijack will cause “excessive” confusion/inconvenience. It’s whether any post is made in keeping with the OP – and that’s all. Many times, posters aren’t very careful about how they craft their OPs, and we’re left to just interpret this best we can.
There are no hard and fast rules for when we intervene. We don’t always agree with flags that are thrown, and those are disregarded. Even among P&E mods, there are differing tolerances for hijacks and how far they can go, though we do try for consistency as much as we can.
I know you’ve asked for exactitude, but I’m afraid that’s the one thing you’re not going to get.
And yes, as stated by @What_Exit, the discussion about polling places is now allowed in the thread. However, I disagree that it was allowed at all by how the OP was crafted. It wasn’t. As I pointed out in the moderation, the hijack was a fine topic of discussion. Just not in that thread, based on how the OP was stated.