Wikipedia says "second-level domains are managed by various government agencies, and generally more strongly controlled" besides the exceptions mentioned like co.uk. Why else would anyone ever have gone for a third-level domain?

If they've recently changed that and I'm misreading Wikipedia, that doesn't change the underlying point that the answer was "you couldn't". Otherwise I've grossly misunderstood the whole post and how verisign is proposing to cancel this person's third-level domain