I've noticed that some questions don't last very long in the HNQ list. For example, this question, Where does the "dysfunctional or broken" meaning of the word "demic" come from? or this one, What is the meaning of "beggar" in this context?. Both of them became hot network posts, but didn't last very long in the HNQ list (you can also judge by the number of views on both questions), just about a day or so (instead of the usual three days).
As far as I know, only moderators can remove questions out of the HNQ list. Is there some other factor that I'm missing?