You're trying to let perfect get in the way of good
The power is never ever ever going to be spent on anything else, the energy used would be purely hydrocarbons in the atmosphere. This is what is happening for decades. Absolutely zero sentiment and protest has or would change that.
Bitcoin mining has changed that. If that is what makes you think of a solution that nobody else has thought of for decades, just because bitcoin makes your tummy ache, be our guest.
> To me, any renewable power going into bitcoin mining, is contributing nothing
I also think it will be helpful for you to get the terms accurate, this benefit comes from stranded energy, using this energy is more sustainable. This doesn't necessarily mean renewable or clean, it can though. Since we are talking about reducing methane emission, this isn't a renewable or clean source, it just has 90% drop in methane and hydrocarbons going into the atmosphere while stripping them apart in catalytic converters just like cars do. This is good!
I don't even have a stake in this game, except living on the same planet as everyone else. And it's getting warmer. Any power spent on bitcoin is power not spent solving more practical problems elsewhere.