Doesnt make sense honestly

Yes but technically the horny stream is literally filled with nsfw stuff, mainly rule 34

Because those NSFW streams aren't NSFW enough.
For example, in the fun stream, it states that "private parts must be covered". As long as you don't see
uncensored genitalia or breasts, it's accepted. Since it's the main stream, moderated by the site mods, this is likely a sitewide rule as well.
Here's an example of a VERY NSFW stream: imgflip.com/m/Boobs
Imgflip staff are aware of this stream's existence (AndrewFinlayson, one of Imgflip's site mods, even is the owner). But the images don't contain nipples, so the stream isn't deleted.

Yes but in horny stream when something is posted people ask for the uncensored, which the nsfw is distributed using memechat

If spreading the uncensored version is banned by the HornyStream mods, then it's not necessary for the site mods to perform any action against the stream.