Earlier quoted context omitted.
The joke is asserting that hot tub streams aren't sexually suggestive. The twitch community seems to love them, so of course Twitch will fight tooth and nail to keep them. But to suggest that they aren't sexually suggestive (and by proxy against Twitch ToS) is an absolute joke. They look like clowns.
They don't say that. Did you actually read what they wrote? It is very nuanced. Their rule is that it can't be "overtly or explicitly sexually suggestive", and they acknowledge that it lies on a spectrum. They have to draw the line somewhere. To some people, for instance the Amish or fundamentalism Muslims, the line is very different from that of typical Westerners.
I again ask, is wearing a bikini, facing away from a camera and touching your toes for $5 not a sexual service?