It's just manipulation of course. They're trying to guilt-trip mods into doing what Reddit wants. Reddit's concern here is obviously not for the poor innocent users being deprived their access to these subreddits. Reddit's concern is maximising the amount of cash that flows into their pockets.
If Reddit actually cared about the users then they would respect the subreddits where users have voted to keep the subreddit private or change the subreddit to NSFW content. But Reddit is not respecting these votes from users, because they only care about the cash flowing into their pockets.