This has happened several times, and it will happen to every asset seized by the government, which is to be sold in an auction and publicly, and this is not limited to Bitcoin. Sometimes the government confiscates cars, home appliances, plots of land, and other things, but I wonder why they were sold to Coinbase instead of being auctioned.There is clear cooperation between some federal institutions and Coinbase, and these payments may be liquidity paid by the government in exchange for data exchange from it, or that the auction was conducted internally and Coinbase won the auction.
This is a common practice by governments of all nations not only in the US. Recently the US government authorities showed interest in selling some assets which include bitcoins seized from a fraudster from my country. The Silk Road Bitcoin will be sold to pay the $183 million restitution fine placed on Ulbricht by the court in 2015. In auction sales, the highest bidder gets the opportunity to buy the lot. Maybe Coinbase was the highest bidder that was why the coins was sold to the exchange.
That will definitely affect the market negatively, and I would be more excited than worried because the price drop is an opportunity to buy. It is an opportunity, and we should take advantage of it instead of fearing it.
I don't think the impact on the market will be massive. The market will stabilize after a few days. This year is an important year for every investor because of next year's halving so any price drop now is an ample opportunity to buy. This news will not cause FUD to well-informed bitcoiners.