Well, that's market information sort of thing. Note that there are many more bitcoins in federal custody. And that the prospect of large amounts of bitcoins re-entering the market will cause some investors to dump their bitcoins.
To add onto your analogy, if they government did print billions more than normal, then investors would project that behavior out, try to figure out what was wrong, and exasperate the effects.
If USA government starts printing extra tens of billions every single day, then investors project that out and that has a significant effect; it was called quantitative easing.
Similarly, if USA government had now started to do sales like this (and larger) every other day, then it would be grounds for some major effects - but they are not; the government does not have many more bitcoins in custody, they have a few limited amounts like this one of less than $20m. Why should such a comparably small sale cause any market disruption? If some $20m re-entering the market does that, then that's a sign of a very, very small and illiquid market.
If any real scale business would start using BTC, gets a few thousand BTC in sales, and wants to swap them to another currency - do they have to think of themselves as 'market influncer' that should be careful on how to sell them so as not to rock the boat; instead of simply immediately getting the current exchange rate for that?
To add onto your analogy, if they government did print billions more than normal, then investors would project that behavior out, try to figure out what was wrong, and exasperate the effects.