I don't expect a massive dump. I even think massive dump is an exaggeration. It will have an effect if sold at once, of course, but Coinbase handled $1.2 billion in BTC/USD alone for the past 24 hours. So, $131 million is not even a tenth of Coinbase's BTC/USD pair. Also, Coinbase has Coinbase Prime, their OTC exchange where institutions are making deals probably in hundreds of millions, if not billions. This amount coming from the US government might end up there. In which case, it won't be shaking the market much.