I didn't read the GP ascribing morality into that statement. They're simply saying that the energy consumption is a market effect -- if it wasn't in the miner's self-interest to mine, they wouldn't.

I read it the same as you, except I hate that line of reasoning to hand-wave things away.

Let us assume a perfectly rational market... should preface all of these statements. That way it triggers us appropriately like "Assume an infinite plane" does.