Of course it is a national security issue. CIA knows the best how to use the internet and trains others to do so. It is risky to have a platform you don't control in your home. People thinking it is privacy issue or pure business idea don't really know what's going on in this world. Look around for all the protests almost all of them organized online. Of course, kids pissing off Trump on TikTok made it easier for him to make the decision.