"assuming that one registers something with the copyright office after something has been stolen"
Time is of the essence in these cases, and the time of creation versus the time of theft versus the time of registering the copyright do matter.
I'm not where I have a nice printed copy of the exact wording (not at the studio today!), but if you create it, post it, it's stolen, and you register it after-the-fact, the sequence must have occurred within a certain number of days. Essentially, you have a grace period after creation to register, even if it occurs after someone uses your creation without permission.