From the abstract, the idea is that we can continue to shrink: "...in a manner in which no thermodynamic entropy is created or passed to the surroundings."
The objection seems to be the "free lunch" assumptions being made about shrinkability.
OpenAI, Anthropic, and Google are way ahead of you. Ask your heart away. I am unsure about open source models, it'd be interesting to know if they're ingesting the law.
The obvious answer to the power problem will be to have the AI design massively parallel exercise bicycle/electrical generator plants that can be powered by all of the people laid off by the AI.
Too much loss and inefficiency. An in vitro ATP fuel cell feed with glucose would be more convenient with the right enzymes… but wait… glucoses will comes from plants and their own ATP uses sunlight as fuel. Replicating that would be much more cost effective than growing plants to feed animal-based ATP. Just as with food, animal intermediaries are inefficient.