It seems a little early to declare them inactive, really. This magazine is 2 weeks old, and given when the blackout started, a lot of the ones in question are 4 days old or less. Not having any activity yet is understandable. And I could easily see deciding to do some of the prep work later after getting a few 503 errors.
I'd say if there's a community you particularly want to do well, post some content there yourself. Volunteer to help out. See if the person who created it is willing to add you as a moderator.
Some of them probably are dead, since the creator could easily have been trying things out here and decided it wasn't for them. But I'd say to give people a chance to return...
The section that says "Results were weighted for age within gender, region, race/ethnicity, marital status, household size, income,
employment, education, political party, and political ideology where necessary to align them with their actual proportions in the population. Propensity score weighting was also used to adjust for respondents’ propensity to be online." kinda sticks out to me, too.