Why does the US government not shut down Reddit when Reddit repeatedly encourages the assassination of Donald Trump?

https://old.reddit.com/r/worldnews/comments/1na5j14/seoul_holds_emergency_meeting_after_citizens/nct8aj5/
https://archive.md/WYDOW
https://web.archive.org/web/20250907060121/https://old.reddit.com/r/worldnews/comments/1na5j14/seoul_holds_emergency_meeting_after_citizens/nct8aj5/