As far as I know, the primary game comm marinanova is locked so that only members of the comm can comment on posts (Marina did this a while back due to spamming). This isn't something automatic, it's an option the mods have to choose. So for the week of the 4th Wall they can unlock the comms and coming the next dayweek they can relock them. Anyone who signed up will still be able to tag, until the mods remove them from the community's membership list, but no one else who isn't a member of the community.