The words are pretty clear on their face--you have to read in the descriptive language of the credit section providing for insurance purchased on exchanges to a person residing in a state which say you get the credit for insurance purchased on exchanges "established by state" to mean on exchanges "established by the state [or the federal government]" which is obviously not what the words say.
Further, the words were put in the statute for the purpose of leveraging the states to establish exchanges on which their citizens would purchase insurance. Which on its face is probably unconstitutional.
It looks to me as though Robert's is wimping on this issue--what needs to be done is to show him that leverage works both ways.
We need to see a lot of letters to members of Congress, members on Judiciary Committees of the House and Senate, asking for investigation of the widely known gossip that Roberts was leveraged on the original decision approving Obamacare because of the illegal adoption of his children.