What he seems to be saying is that by design proof of work incentivizes fully saturating available energy, and that the only world in which it won’t compete with other uses of energy is one in which we have more than enough capacity for all other uses, plus excess, and that until we’re there being in favor of devoting energy to proof of work is functionally equivalent to being against preventing emissions. I’m unaware of the debate, so as a lay man I admit I don’t know if the argument is old or not (and I think how old it is is irrelevant to whether or not it is right), but I find this line of argument compelling.