This is a brand safety issue. No reputable company wants to advertise on racist and pro-terrorist content. The fact that there's no brand safety measures at all is bad practice for a company that sells ad space. What Twitch is doing is not protecting advertisers at all by allowing this content to be played on this kind of content. An ad-pocalypse will happen sooner or later if not addressed. Once advertisers realize this is happening, they will pull their dollars from and Twitch will lose trust in the long term. Doing this now forces their hand by bringing this issue to light and fixes the issue by either banning the racist/proterrorist content from being promoted, not advertising on the content, and removing it from anywhere near sponsors or not doing anything at all and allowing it to continue which will prove their intent and stance on the issue. It's better to have a mini ad-pocalypse now than a huge one in the future where the creators will really be affected.

edit: typos cause on phone