Either way. If there was a law with no specific intention, then there is no law, at all.
If they meant what the law says, then they should follow it As written.
Currently they are saying that the backup plan if the states didn't set up their own marketplace was for the federal government to set up a marketplace for them and thus would inherit the incentives provisions from the state plan.
The judge should just say that the written law means nothing and the actual way it should be interpreted is:
“everyone gets subsidized healthcare based on ‘from each according to his ability, to each according to his need’, at the discretion of president Obama, HHS, and the IRS”
because, de facto, that’s the way they’re running it.