But remember - the day before Roberts said that, he remedied the badly written ObamaCare law in order to keep it in place and intact.
Roberts is many things, but “right” is not one of them.
The law is slightly vague as written. “states” could mean state of Alabama or United States. If the law explicitly had said “None of the 50 states will get federal subsidies if they do not set up an exchange in their respective state”, then Roberts or anyone can only interpret one way.