Okay, but if you steal a phone on the subway, why would you even bother unlocking it? Just sell it on ebay as a locked phone. Some bored teenagers will buy them up, unlock them, wipe them and then resell them for a few dollars more.
You need to be able to sign in with the Apple ID to remove the association.
I've already done that service for another, using some auto-unlocking tools. Takes all but 5 seconds, including USB negotiation. And it even gets past sim-locks.