Not "you" -- this guy was a unit chief. It's plausible that a smart underling played him into making an ass of himself - after all, somebody trying to claim copyright of a federal document (which is by definition in the public domain, in the US) must have quite the sense of entitlement, and likely an ego to with it. Being a slow-burning prank, the underling was likely to get away with it scot-free; who knows, s/he might actually be one who eventually tipped off reporters.
(Or, since the filing happened in 2010 when, I presume, the legal battle over it was in full swing, it might have been a last-ditch attempt at keeping it private: "Sorry, we can't release it because it's copyrighted by the author". I have seen similar arguments used in FOIA refusals used in the past -- "sensitive commercial documents" and all that.)