US government just moved 10,000 bitcoins to an exchange, coinbase prime. While this might be worrying for others especially after the German government moving their own bitcoins, I advise everyone to remain calm. The 10,000 bitcoins taken in custody from the Silk road case were transferred to an exchange but not with the intention of selling them.
It's more realistic to assume that these bitcoins will be sold, just a matter of time, when it will be sold only. Assume it will be sold, you will see no reason to panic as in Bitcoin market, there are buyers and sellers and many bitcoins changed hands on daily basis.