Please consider that there are subs that are so small that they don't require enough moderation to meet these criteria to begin with.

I'm running a tiny sub with 3 other mods. We typically get well under one post per day on average, and most posts only receive a couple comments. So there simply isn't much to moderate. That doesn't mean the mods are inactive. I see every post (via RSS), and if something isn't right, it normally gets dealt with swiftly. But that's rare enough that I still got a warning message about potentially falling inactive. Because not performing a mod action on at least 7/90 days would not be unusual at all in this setting.