The real answer is that it depends on what the Supreme Court says.

There's a valid legal argument to be made here either way; that the government has some amount of leeway to censor foreign propaganda, or that the first amendment prevents it from doing so at all.

We'll really just have to wait and see how they rule on it, because the issue will definitely make its way there at some point in the near future.

It's also likely that the verdict won't have a neat and tidy partisan breakdown, so the final result will be hard to predict.