Ew. The content problem on TikTok was never the protocol, it's that 99% of short-form video is brainrot slop regardless of who hosts the servers. Slapping ActivityPub on it literally solves nothing for humanity.
I'm hopeful that the decoupling of algorithms (feeds) in ATProto can change this equation. For the tiktok clones and all the other apps.
If TikTok was decentralised then the instance that you are a member of could de-prioritise videos from those instances that were allowing the brainrot slop.