The original video is still the original poster's comment, and thus still 230 protected. If the kid searched specifically for the video and found it, TikTok would have been safe.
However, TikTok's decision to show the video to the child is TikTok's speech, and TikTok is liable for that decision.
That's going to be hell for Google. Well, maybe not, they have many and decent lawyers.
How is my interpretation incorrect, please? TikTok (or any other website like Google) can show a video to a child in any number of ways - all of which could be considered to be their speech.
That said, this is a statement completely unsubstantiated in the original post or in the post that it links to, or the decision in TFA. It's the poster's opinion stated as if it were a fact or a part of the Judge's ruling.
"We reach this conclusion specifically because TikTok’s promotion of a Blackout Challenge video on Nylah’s FYP was not contingent upon any specific user input. Had Nylah viewed a Blackout Challenge video through TikTok’s search function, rather than through her FYP, then TikTok may be viewed more like a repository of third-party content than an affirmative promoter of such content."