Twitch Updated their Sexual Content Policy:
- Changes: Certain content now allowed with labels
- Artistic Nudity: Permitted under Sexual Themes Label
- Game Nudity: Contextual; labels necessary
- Body Painting: Acceptable with appropriate label
- Mature Games: Label generally covers content
- Stream Visibility: Impacted by content labels
Twerking, grinding and pole dancing are now allowed without a label.
I think it has to do with the fact that some investors, payment providers and banks refuse to associate with anything that could be seen as sex work. That was why even OnlyFans was about to ban sexually explicit content 2 years ago.