There's no single set of "international law" in the sense of national laws, state laws or local laws. There are only agreements and treaties between nations that are applied within those nations. As such, what "international law" applies depends on which nation you're in or from or if some nation's law enforcement have jurisdictional reach.

More to the point, nothing about this decision implies statelessness. Every visa applicant is a citizen of another foreign, non-American, nation. Being booted out doesn't make them stateless. They couldn't have applied for a visa if were stateless.

Note, I do agree that this suspension is unfair and a bad idea. But tossing out random accusations that imply that international law is being violated or causing people to become stateless doesn't help our case.