it isn’t in theory. but admins are saying it violates moderator code of conduct by vandalizing a community (which is against reddit rules). Private subs are allowed, but sub squatting and vandalizing are not. theoretically, they could just invite a few people and have a “low activity sub” but still engage as normal while keeping the sub silent. thus no vandalism occurred, nor squatting, but rather just a change in preference of the community (being more private/exclusive).