Both articles should simply state the lifetime carbon footprint of ICE cars and EVs. That is all that matters in this context - break even mileage and energy efficiency are secondary concerns.
GP’s point though is that the footprint of EVs is constantly changing. ICE cars can only ever work by burning fossil fuels, which inevitably results in a certain amount of emissions per gallon of gas burned. That’s not the case for EVs as the electricity needed for them can be generated in many different ways, some resulting in more emissions than others.
It seems that for this analysis using the current and projected fuel mix would make the most sense. There is no option at the pump purchase gas made from offshore crude for example.
The projected energy mix for the next 10-20 years is likely known with some certainty. I suspect that the total carbon footprint of an EV purchased today is something that can be reasonably estimated