This would seem to be the main argument of that second article you posted summarizing the economics around PoS. The idea is that if you’re backing your crypto with itself (like in a PoS), the value that is locked in the staking system could be doing something else. (This is a very real point in that it doesn’t help decentralization—the same people that would stake their coin could spend that money mining Bitcoin.)
But it doesn’t seem to address any points in the conversation around the ethics of using electricity as a basis for proof of work.