This is correct.  Let's say the US says operating a mining rig, taking part in block exchange, and buying selling btc is illegal, then they've just birthed massive amount of credibility to the world wide system.  They could also fix the price of btc in a buy back in the form of a safe harbor reimbursement, and then make it illegal, but then the US ends up as a massive stake holder in btc... which opens up another can of worms (some other time).

If you were to ask me truthfully what I think is behind bitcoin.  cia.  I think they know the fiat system is on its way out.  they know that it is a matter of time before someone else figures out that proof of work computing is a far more efficient system at storing transactions on a multi billion node system.  they leak it out to the world after they've mined almost 40% of the total btc to ever be minted.... and then they welcome the arrival of the new banking world system holding 40% of the assets... game on until we figure out another more efficient method for value transactions.

No matter what we're in an exponential curve of technology development.  We're kind of at the infancy of the great swing upwards.  It doesn't surprise me that networked systems on a common protocol could turn the archaic baking system on it's head.