Why should Obama think in terms of what the Supreme Court might say about his power to single-handedly raise the debt ceiling?

Jeffrey Rosen wonders, noting that the Supreme Court would probably not hear the case.

And even if the justices did agree to hear it, the conservative justices would be torn between their dislike of Obama and their commitment to expanding executive power at all costs. If all the justices are true to their constitutional philosophies, the Court would rule for Obama by a lopsided margin.

In fact, it makes plenty of sense for Obama to refer to what the Court would say even if he doesn't believe the question will end up in court. Why shouldn't he act deferential to judicial interpretation when it's not obstructing anything he presently wants to do? It's exactly the right time to strike that pose if he thinks it's flattering.

Anyway, Obama left himself plenty of room to shake off the deference if and when he wants. All he said was: "I’ve talked to my lawyers... They are not persuaded that that is a winning argument." Not only could the lawyers later become persuaded, Obama could make his own decision disagreeing with his lawyers, and he could decide to rely on a reading of the Constitution that he believes is correct even if he's not persuaded it's a "winning argument."

Now, is it true that the Supreme Court would say the President can, on his own raise the debt ceiling? The constitutional hook for this power is "The validity of the public debt of the United States, authorized by law … shall not be questioned." Rosen says:

All four liberal Justices are committed to a vision of “living constitutionalism” that interprets the historical evidence broadly...

He says a bit more than that, but not much to find 4 votes for presidential power. Only one more needed.

What about the conservative justices? Here the divisions in the conservative ranks might become relevant. There are three distinct strains of legal conservatives on the Court: the tea party conservative, Clarence Thomas, the libertarian conservative, Anthony Kennedy, and the pro-executive power conservatives, John Roberts, Samuel Alito, and Antonin Scalia.

The tea party conservative, eh?

Of these five justices, Thomas is the only one whose judicial philosophy might lead him to side with Congress over Obama. As someone who believes that Congressional power over the purse should be construed strictly, Thomas might conclude that Article I gives Congress, and not the president, the power “to borrow money on the credit of the United States”—a power that it has exercised by establishing a debt ceiling. The debt ceiling doesn’t repudiate the debt or question its validity, Thomas might hold; it simply threatens default by prohibiting the president from assuming extra debt beyond what Congress has authorized. According to this argument, Obama’s unilateral decision to take on additional debt to avoid a government default would not represent debt “authorized by law,” as the Fourteenth Amendment requires, and therefore wouldn’t be justified by the Amendment.

Isn't it funny how this "tea party" philosophy just sounds like a fair reading of the text? But only Clarence Thomas is crackpot enough to do that! I added the boldface to highlight what to me seems like the obvious interpretation: No one is talking about questioning the validity of the debt! When you fail to pay debts, you're not claiming they aren't valid. Why wouldn't all the Justices say that? Why would that inapt clause take precedence over the specific and clear clause in Article I, listing among Congress's powers the power "To borrow Money on the credit of the United States"?