My recent question about an APC UPS was closed as off topic ("This question is not about computer hardware or software, within the scope defined in the help center.") I flagged another UPS-related question as off topic since it was a very similar to mine. The flag was declined. How can I decide which UPS-related questions are on topic here?

If I'm right both questions could belong to the

electronic devices, media players, cell phones or smart phones, except insofar as they interface with your computer,

off topic reason.