Foreign propaganda bots are just as present on US social media, and US social media amplify them just as much.

So where exactly is the meaningful difference here? I don't see it.

The actual difference is that US does not see the money from Tiktok, and blocking tiktok is a convenient excuse to give their propaganda platforms a competetive edge.

Actually doing something about the fundamental problem of foreign influence through the internet would basically destroy sillicon valley, and no politician wants to be responsible for that.