The Streisand effect is not wanting people to know something, and in trying to prevent that drawing attention to it.
That’s not what is happening here: everyone knows there’s a bunch of basement trolls who stream violence (which is of course against tos), and from twitch’s POV publicity is a win:
* they get public appearance that they’re trying to do something about.
* the specter of being sued may discourage some people from abusing their platform
The Streisand Effect implies that the subject did not want the publicity but got it by trying to hide or cover up something. Here Twitch wants people to see that they are taking action. Now if the publicity leads to additional trolling of their platform thus exacerbating the problem, then you could make an argument that this scenario fits the Streisand Effect.
That’s not what is happening here: everyone knows there’s a bunch of basement trolls who stream violence (which is of course against tos), and from twitch’s POV publicity is a win:
* they get public appearance that they’re trying to do something about.
* the specter of being sued may discourage some people from abusing their platform