"Amazon took unilateral action to punish authors" ?
The contract between Amazon and Hachette expired.
They started negotiating a new contract. They can't agree to terms hence Amazon limiting Hachette's stok because, well, they no longer have a contract to sell Hachette's books on Amazon.
There was nothing "unilateral" about it. Amazon doesn't agree to Hachette's term. Hachette doesn't agree to Amazon's terms.
Amazon didn't "punish" authors. It didn't even "punish" Hachette. 2 giant companies failed to agree on distribution terms.
It's regrettable that authors are collateral damage here but how do you put the blame fully on Amazon and none of it on Hachette?
Especially given that Amazon is the party that proposed a way to compensate the authors during negotiations. 3 proposals, actually, all of which Hachette rejected. Because Hachette cares about their authors so much.