He may still be able to use it. After all, that game isn't Nation States but NationStates. The space may be a minor issue, but I think from a legal standpoint game titles, like book and song titles, are considered fair game unless you have a truly unique title and the difference in how it's written may be enough to tip the balance.
Earth Empires may make people think of Empire Earth, and since the EE series was pretty forgettable I'm not sure he'd want to have anyone associating the two.
