There is no money there. Advertisements won't be shown next to those posts. Or at least non-adult brands -- Apple, Microsoft, BMW etc won't want to have their ads shown next to NSFW content (if they are still doing business there). Twitter/X is creating infrastructure and providing bandwidth for content that will barely give them any revenue in return.
Plus, companies will think more carefully before showing ads on Twitter/X -- even if their ads aren't shown next to NSFW content, if the platform is lax on moderation (non-consensual content etc) they likely don't want their brands to be associated with such a website.
Well, unless in the case where people who view NSFW content a lot are also active Twitter users otherwise and would click on "normal" ads. But I don't think that is going to happen.
Plus, companies will think more carefully before showing ads on Twitter/X -- even if their ads aren't shown next to NSFW content, if the platform is lax on moderation (non-consensual content etc) they likely don't want their brands to be associated with such a website.
Well, unless in the case where people who view NSFW content a lot are also active Twitter users otherwise and would click on "normal" ads. But I don't think that is going to happen.