This is clearly the main motivation. If the CPC was so serious about curbing emissions they would put a high environmental tax on coal power plants and the bitc

This is clearly the main motivation. If the CPC was so serious about curbing emissions they would put a high environmental tax on coal power plants and the bitcoin mining would quickly wind down as a result of higher electricity prices. The CPC requires a firm grip on monetary policy (and capital flows) in order to stay in power (and prevent a yuan devaluation).