From my point of view there should be a "do no harm" policy in place.
https://www.law.cornell.edu/uscode/t...t-I/chapter-13
As a private business, I would disallow anything remotely in violation of these laws even if there is only a virtual threat involved.
ICANN is the NGO that operates the internet now and every nation can apply its own laws to this world wide 'utility'. ICANN's only tasked duty is to run the infrastructure of the Internet and not to regulate it.
So, again if you don't like the laws change them -- that is the limited constitutional right you have in USA. In China I don't think you can petition the government or obtain redress in the courts.
If your question is should fringe elements be allowed to fantasize, conspire or actually plan unlawful acts on the internet? The answer is no or as the law applies in that jurisdiction.
If neo-Nazis want to promote the annual company picnic that in itself is a lawful action. If someone hypothetically started a site for the purpose of child pornography is that protected speech -- even if all they do is fantasize or act out to conspire? Maybe, their prosecution of a crime may be a reach -- but is that freedom of speech too? What are their rights? I say none as they intend harm to people -- private businesses should have the right to limit speech on their 'virtual' as well as physical premises.
Or, the the crude colloquial, "if you don't like it -- hit the bricks"