Many people predicted the opposite of this would happen though. That when coinbase users got their BCH freed up they would dump it on the market and tank it, and part of the announcement includes freeing up users' BCH.
People originally assumed that Coinbase were only going to allow people to withdraw their BCH and not open up trading, because that's what Coinbase had said they were going to do right up until the point when they suddenly did open up trading on BCH.
