Couple that with the fact the fact that Pirate is probably not his real name etc etc and proving that he is the one who people sent all their coins to will be difficult. Added to which, most of the investment was done via pass throughts or secondary agents etc.
You can see that it is not simple to investigate or prove and thats if any law enforcement is actually interested.
Oh, so theft is only theft if it's a currency? That's good to know, can I have your address real quick? I'm sure you have lots of non currency items in your house.
Tangibility and legal tender status aren't the issue.
BTC are not only virtual items, they are virtual items produced solely by voluntary, willful participation in an ongoing experiment requiring the affirmative consent of us test subjects.
Think of them as 'almost' a real thing that may be stolen. Beta-testing stage proto-property, if you will.
You can "steal" bitcoins exactly as much as you can "steal" monopoly money from other players during the game. IE, not at all (except in the metaphorical sense).
Doing so is against the rules of the game, and may cause people to no longer wish to play with you again, but never becomes a real-world legal issue.