Hi Mr. Law, I stole a million USD worth of BTC and now some angry guy is at my door asking for it back, help!
I guess it goes like this:
Hi Mr. Law, this crazy guy says I stole some kind of made up internet money that I never even heard of and is at my door asking for it back, help!
Yeah, some "made up internet money" he can exchange at any moment for probably close to one million dollars of real world money, that was stolen. Maybe there are no provisions in place to deal with it, but if I was being threatened after stealing it, I'm not sure the law would be the first place to turn. You would have to explain to them what you had done, which is in effect, theft of $1m USD.
Wouldn't be the first time someone in the US has been prosecuted for BTC theft.