GP's point is about the tradeoff that switching to electric cars versus ICE provides, and BTC does not.
Let's assume that switching to electric does not, itself, cause an increase in total cars on the road. Let's also assume that both ICE and electric vehicles require roughly equal amounts of energy to travel equivalent distances (this is probably not true, but helps in the analysis). The tradeoff between an ICE or electric vehicle, then, is which produces more carbon emissions for the same amount of energy: the gas/diesel combustion engine or the power plant?
If the plant is more efficient, converting to electric vehicles will produce a net reduction globally, but a net increase locally (at the power plant) in carbon emissions.
If it's equal, then we just shift the source of emissions to the power plants.
If plant is less efficient, then there will be a global increase. This is the worst case, it's also not the likely case.
This gets improved later with the ability to switch to cleaner energy production methods than burning oil, coal, or natural gas. This is not an option if we remain with ICE vehicles, we can't put a wind turbine on them or a nuclear reactor.
BTC doesn't trade anything, it just increases energy consumption (and therefore production). In the near term, at least, BTC will increase carbon emissions because that's how most energy is produced. Not just exchange the location of emissions. BTC isn't replacing oil burning bank ledgers. It's just consuming orders of magnitude more energy to do a similar job.