If SCOTUS can twist these words what stops them from twisting ANY words?
Except that if "State", only means individual states, then many of the constitutional amendments - including the second - fall apart on the federal level.
That's why in laws (especially 2400 page monstrosities like this one) they have sections on Definitions to specifically say whether "State" means "50 States", "50 States + US Territories like Puerto Rico", or "50 States + Territories + District of Columbia", etc.
In this case, the law was originally drafted to deal with State-level exchanges. A Federal exchange was an afterthought one they didn't expect/hope would be used. (And according to Gruber, was intentionally left out of this clause.) Whatever the case, the courts should be rewriting when it's a clear cut, cut-and-dried case of an error. As long as there's a plausible rationale for why the text is the way it is ("To discourage States from relying on the Federal exchange, at the cost of the Federal funding that we'd otherwise be giving to the citizens of that State to help with the insurance fee we're forcing them to pay"), we should be relying on the text.
Typos can indeed lead to ludicrous conclusions that can be corrected judicially. This was not one of them.