Just wanna say that the UK has actually done this for like, decades now.

Consumption of content from "proscribed organisations" or something to that effect. You'll almost certainly have the content on your local machine in cache or something and that counts as "owning terrorist content" or something like that.

This was put into place before this kind of thing was just commonplace on every single social media platform. I haven't really seen it used since afghanistan/iraq when we would get suicide bombings here in the UK, but it's something that we've been doing a while and could easily be re-used for this kind of thing..