Yes and no. Yes it should be up to US law on how forums are conducted. Such as braking of any laws. The real question is what does it mean to "disrupt a public forum"
Because these social media's are political forums. Politicians do use them to communicate with citizens. The US supreme court has already ruled on that.
They should be under freedom of speech laws.
I don't think there is a real clear answer to what "disrupt" means. Which is left to the forum operator to decide. That is the real issue. Facebook gets around this by claiming it's not a forum at all and can delete anyone they feel like.
Do you understand the US Constitution prevents the government from passing laws that restrict speech? US law should not govern any private speech. Calling it a Forum does not change the law. It is still a privately owned forum whose owners are free to restrict or promote speakers as they wish free from government control.
What are the “freedom of speech laws” you are referring to?
Can you find one instance where government regulation has helped the cause of liberty and conservative speech?