But there are American users making and viewing content on that platform.
The physical equivalent would be if China was hosting a TED-talk-like conference where anyone can come and hold a presentation, and after certain kinds of talks became popular congress would tell them that they are no longer allowed to let Americans in, neither to hold presentations nor to listen to them.
Technically that doesn't violate the constitution, but it's not difficult to argue that it does violate the spirit of the constitution
The physical equivalent would be if China was hosting a TED-talk-like conference where anyone can come and hold a presentation, and after certain kinds of talks became popular congress would tell them that they are no longer allowed to let Americans in, neither to hold presentations nor to listen to them.
Technically that doesn't violate the constitution, but it's not difficult to argue that it does violate the spirit of the constitution