That would require long term planning that is difficult for government officials to do. The General Schedule pay grades are more like time clock punchers that worry more about their benefits than doing their jobs. Elected officials can only see forward to the election. If they had a real grasp of future economics the 2008 recession would have had a very different outcome. Never make a plan today for what you can bail out tomorrow.
You put that nicely there, like a little New Years poem to the government.
Another thought just came to me: They can't sell off anything illegal, so they can only sell of BTCs as long as they are legal.
Which would mean BTCs stay legal in the US at least till some time after the end of the trial.
The US Government has made it pretty clear that the use of virtual currencies, and specifically bitcoin, is NOT illegal. And if their plan was to "make it illegal" while in the world would they do that in the first place.
The US Government is still trying to figure this out and what to do about it. You can actually read the latest here.
Bitcoin: Questions, Answers, and Analysis of Legal Issues
http://www.fas.org/sgp/crs/misc/R43339.pdf
If I was going to worry it would be about the tax implication of bitcoin. The United States Government Accountability Office issues a report to the US Senate Committee on Finance entitled:
"VIRTUAL ECONOMIES AND CURRENCIES Additional IRS Guidance Could Reduce Tax Compliance Risks"
http://www.gao.gov/assets/660/654620.pdf
Here is a podcast with the James R. White, the GAO's Director of Tax Issues
http://www.gao.gov/multimedia/podcasts/654442