Tell me that again AFTER having actually read the paper.

I don't understand how a paper could contradict basic physics. Energy spent mining bitcoin is energy not spent doing something else. There are other ways to encourage more renewable energy production (e.g. government subsidies) that don't involve taking the resulting energy and turning it to waste heat. Even low-efficiency energy storage methods (like pumping water up a hill) are more efficient than simply turning the excess energy to heat.