Okay, but the 'if' there is true. Bitcoin is currently inducing demand for coal and gas plants, which is very bad. It's unclear when it'll stop doing that, if it'll stop, and a hypothetical future in which Bitcoin starts incentivizing the good thing instead of the bad thing doesn't change the truth value of the current bad thing.
(We've also fixated on coal burning, when there are oodles of other great reasons to not like Bitcoin. A small handful of them have been listed elsewhere in this thread.)