SCOTUS explicitly avoided ruling on this justification, and it seemed at argument that even some of the conservative justices were uncomfortable with the free speech implications of it.

I think the question "What is Tiktoks speech?" was raised. And the answer, "the algorithm" didn't really strike home.

So I read it like they didn't interpret this as a free speech issue at all.

It's not a top down broadcast and the SCOTUS has a hard time wrapping their head around 250 individual people receiving individualized content with no oversight or necessity for accuracy.

That justification also seems like it quickly can be used to shutdown access to VPN services hosted elsewhere like Mullvad.