But we really don't care about that factor of 2. It literally doesn't matter, whether Bitcoin wastes half a Luxemburg or a full Luxembourg.

And, iirc, then they estimated total consumption from well-funded and very active mining pools. I.e. exactly the operators that you would expect to run the most efficient mining equipment. Meaning all you do is being overly optimistic, as in "we claim mining uses less energy than it actually does"

The statistic you're poo-pooing puts error bars that are a factor of 2× in either direction. Tolerating that degree of error bar isn't all that difficult, and if you bothered to continue to read the article, you'd discover that the author themself discusses possible error bars, and deflates the estimated operational cost of bitcoin miners by half anyways.

And, FWIW, the kind of methodology that was used to produce the Bitcoin energy consumption is the same kind of methodology that is used to produce statistics like GDP, inflation, employment--basically every macroeconomic indicator. If you're going to complain that you can't quantify Bitcoin's energy consumption, then to be intellectually honest, you need to complain that the true inflation rate or the true size of any country's economy is impossible to quantify as well.

Again, though, that's just not true. The hardware is well-understood and easily measured. Sure, there is slop in the measurement (how much of the fleet is using platform A vs. platform B). But those are comparatively small numbers. Sure, like you say, we might have a factor of two lurking in there (seems high, but I'll grant it).

But a factor of two wouldn't change any of the analysis! If the article said "60 TWh" instead, would that be any less horrifying? No, it wouldn't.

We don't know what hardware is on the network and we don't know how all of the power is generated. If it is 60TWh of clean energy that isn't being used for anything else, who cares?