Like I said we'll give a long enough time period that someone passionate about their community would have populated it by then (with some posts atleast). this is mainly to prevent people to squat on multiple popular community names with no intention to curate a community around it.

Maybe you could post a little introduction/welcome text post on the communities you want spared.

As long as there was warning, that seems like a good way to spare small communities that haven't gotten off the ground while getting rid of squatters who aren't interacting at all.