They still have the right to distribute it. It's not like reddit, who not only claim the right but also apparently claim ownership of any content you publish there, while providing no consideration (payment) in return.
However, as you say, they have the right to deny you, and by copying you are subverting their rights. That's still not theft, though, which is why copyright infringement is a separate offense.
Theft is a crime, copyright infringement is a civil matter.