I think his point is that the mods of the sub have done their best to enforce the rules, despite missing a handful of very lowly upvoted comments here and there.

Thus "they" (the people who run the sub) have not broken any rules, just some bad actors which presumably would have been dealt with if their posts got more attention.

If random users making bad posts that almost no one notices in highly active subs constitutes a total subreddit ban, then all subs would end up banned.