Let me walk you through your own example....
I'm a terrorist. I register my drone as John Smith. I put in some address and a phone number to a pre-paid cell phone that I bought for $20. This took me all of 45 minutes (ok, an hour if the cell store is far away). I then create a drone to deliver a bomb. Now, I'll just ignore the obvious situation... I create a bomb that is delivered by the drone. What I do is spend a lot of time, not creating a bomb that I can blow up upon delivery (because that would be _way_ to easy and I'm a much more James Bond villain type of terrorist)... I take the time to create a bomb that only blows up with the battery is removed. Now, I fly that drone to some busy spot and land it. A first responder then gets the drone and calls me (remember, I'm a sophisticated terrorist so I put the registration on the drone (because that is the only situation where your scenario works.... I'm a law "abiding person" who put their registration on the drone). The first responder then calls me and as a "law abiding person" I tell them, yeah... my bad, I accidentally flew that drone and landed it next to the White House. So now what? They are safe to open the drone? Oh? They don't remove the battery? Well, without the registration they don't open the battery either. However, under my frame of mind, they treat the drone as it could explode. Who's going to keep that first responder alive in this situation... you line of thinking or mine?