By giving the President the power to ban websites, not just apps, it opens up a whole new can of worms.
Instead of targeting foreign adversaries directly, the law holds US (or offshore) internet hosting services and app stores responsible for any breaches in security or privacy.
This is a Trojan horse that could lead to censorship and control over what people access online.
This kind of stuff will absolutely be applied selectively. The whole point of a law like this is to let you shut down sites that are inconvenient.