With which part?
Protecting "his brand" with an unneeded apology that casts blame at Twitch? It's just acting in his self interests to further his career. Twitch can promote whoever they want on whatever page they want on their platform, to be honest.
As to who to blame, it's people abusing the platform to stream inappropriate content. The person streaming must have had related content in the past, was flagged by an algorithm because they were getting a ton of views in short time, and simply gamed the system to get pushed to the front of the recommendations. The same thing happened with Artifact awhile back. The only option is to manually approve and continuously monitor each and every stream.
Twitch didn't put porn on his page on purpose, ruining their reputation, as a petty spiteful insult. Ninja's statement is about as interesting and thoughtful as any piece of pandering corporate PR. This entire thing is nothing for everyone involved.
Correct