Rare it is that I am in substantial agreement with any Volokh Conspirator. But with the exception of the next-to-last paragraph, I think Jacob Levy's item on the Pledge captures my feelings pretty well. Where we part company is the idea that the government could reasonably request, much less demand, a citizenship oath at 18.
That said, I guess I have to admit that we already a de facto oath requirement at majority in most states—for those who wish to vote. I've had to swear to preserve and protect not just the Constitution of the USA, but that of two different states in order to exercise my franchise. Is that in keeping with a vision of the Republic that situtates sovereignty in 'We the People?' I can see arguments on both sides of that one.
And since, as it happens, I think that state and federal constitutions are a Good Thing, even when imperfect, I'm certainly not about to make an issue of it.