This is not how sport teams work, this is how every enterprise works. When a monster/trascendental deal is in place, ownerships are who make the last call.
This is on JH and Luchino all the way, for good or for bad. The Panda signing. The HR signing. The epic fail for Lester. The trade with LAD, etc.
GM's role is to make the diligences and suggest, that's all. I only wonder whether BC told to the owners that the 70 M offer was a ridiculous approach at the time or not.