I'm not a lawyer, but it doesn't take much reflection to see that this is a transparent attempt to do damage to Obamacare. The fact that this has even reached the Supreme Court doesn't give me much faith in the institution.

Let's do a thought experiment here: let's say I was a legislator crafting a law to grant same sex couples federal marriage benefits. Due to the legislative challenges, the law is crafted very quickly and gets hurried through Congress, and somebody doesn't noticed that a crafty intern slipped into the legislation some sort of provision that claims that marriage is only defined as between two heterosexual couples. Now, clearly, we would have to throw out that part of the law, right, because it contradicts everything else written? It wouldn't be a threat to the entire piece of legislation because there was one stupid line written by one stupid person? I hope Scalia wouldn't be standing there saying, "The question is whether it’s the statute that they wrote." I mean, really? How can we be in such a situation where a court is seriously considering overturning a giant piece of legislation because of one line that was clearly written incorrectly?

But, from what I understand, case law doesn't have such a transparently stupid approach to all legislation (we must follow the "plain meaning" in all cases, not matter how absurd!) And, in fact, that's the argument the government is making. Here is Michael Rosman's summary (who is a supporter of overturning the law):

In King, the federal government does not seriously argue that it would be absurd for Congress to limit subsidies to individuals in states that have state-operated exchanges (although it does argue strenuously that that is not what Congress meant). Rather, it suggests that there are other provisions of the ACA that would be rendered absurd if the phrase “Exchange established by the State” were given its plain meaning.

Now, maybe we can find some way to make the law still make sense if we assume the plain meaning of the statement, but the truth is we can make an argument for basically anything that we desire. When you're getting to the point of destroying a controversial piece of legislation because of an arcane dispute about matters of basic interpretation, the right approach is to kick it back to the legislative process and wash your hands of it. As Roberts pointed out, if a conservative president takes office, they can go ahead and interpret it the other way and take subsidies away from their own constituents. We shouldn't be settling this kind of thing in the court, and we definitely shouldn't be settling it for such transparently silly reasons.