Barring a particularly convincing argument by the yet-unnamed sponsor, I'm afraid I will also have to oppose this bill, for pretty much the opposite reason as Yankee. As a general rule, I'm not a fan of state-imposed waiting periods for personal decisions; from personal experience, I can testify that a quick and clean break from the game is often the best solution for those for whom the heckling and pressure of politics has become too much, and I don't think Congress should be in the business of telling them they can't deregister immediately because a dozen or so insiders in Nyman have decided their "overreacting" or whatever.
But if one is going to restore the restrictions on returning, which could at some point happen, I would prefer this waiting period be in place then not be. At least now the only consequence has is the loss of whatever office said person held when they deregistered.
I understand this argument, but I'm afraid I find it about as convincing as you find mine.
What this ultimately boils down to is Congress trying to protect people from their own bad decisions. In certain contexts, this may be necessary or even desirable; but I don't think this is one of them.
I should also add that I am not at all convinced Congress has the constitutional authority to tell persons they
must remain registered with the Census Bureau for a minimum period of time; that goes far beyond the power to "to establish uniform laws of naturalization" established under Article III(6).