The SEC is going to start charging an exit fee on certain types of money markets to keep people from panic selling. As far as I can tell it's retroactive which would be a serious violation of contract law (not that anyone cares about rule of law anymore).
Also they are going to add something called a floating NAV. I'm not sure what that is but I know investors don't like it. And guess what, US Treasuries are exempt from this "floating NAV" to try and entice more people to invest in treasuries.
So if the US is in such supposedly rock solid financial footing, why would they need a mechanism to prevent people from selling dollars?