Energy consumption is energy consumption. While you might be connected to a grid where renewable sources are accessible, you are still straining a grid which could cover for an area which uses less clean energy sources.
But it’s not like every mining rig is connected to a source of renewable energy. It’s untraceable, which is part of the concept behind bitcoin. It should be obvious that a decentralized, untraceable, energy intensive cryptocurrency is not somehow controlled to be driven primarily by green sources.
I’m convinced it’s all just an attempt to improve his statistics, making the average age of people he punches roughly around his own age.