You just need to be a moderator of any subreddit. The subreddit itself doesn’t need to be NSFW. The idea is that moderators could have a need to evaluate NSFW content on user profiles to make moderation decisions.

There’s an update that makes you login again. It installed for me yesterday. After the update get an annoying locked post from u/redditmaturecontent telling you to go to Reddit access NSFW content now.

Oh, that’s interesting. I was hoping a scraper would emerge. Stealth’s scraper (currently) doesn’t seem to actually display content that is marked nsfw. Maybe they haven’t yet figured out how to detect/accept the confirm 18+ barrier on old.reddit.com.