Well, he doesn't blog anymore but he gave me permission to reproduce this email he sent to me, commenting on the case:
Finally got a chance to read McCreary. What a magnificent opinion. I think it's the best opinion I've ever read on Establishment. Impenitrable logic, meticulous research, witty, magnificent.
Sad, by contrast, to see Scalia start off by waving the bloody shirt--and with a blatant misrepresentation: he says that while some countries are explicitly secular, "This is not, and never was, the model adopted by America. George Washington added to the form of Presidential oath prescribed by Art. II, §1, cl. 8, of the Constitution, the concluding words 'so help me God.'"
--now, wait a second! Washington "added" to the form of the oath because that phrase was not IN the oath--in fact, it would have been illegal to require that, because the Constitution explicitly forbids religious tests for holding federal office! Washington was free to add "so help me God" because he had the right of free speech like any other person, but the "model adopted by America'--that is to say, the actual words of the Constitution, FORBID us to compel a president-elect to say the phrase "so help me God." Come to think of it, they forbid us even to require the word "swear"!
None of the other examples Scalia cites have even the slightest Constitutional pedigree, and one might add to them the first Congress' creation of a chaplainship--something Madison himself explicitly declared to violate the Establishment Clause, in his Memorandum on Ecclesiastical Establishments! Scalia's opinion consists largely of assertions that, because people have in the past acted in a ways that find no constitutional warrant, with the support of lots of people, therefore there must be no constitutional bar on such acts. Absurd.