Note quite true, the 12v battery may power the fan for the heating system but the main battery is used to generate the heat* (it may go via the 12V battery). The major difference between ICE vehicles and electric vehicles is that an electric vehicle produces no heat when it's not moving, and a combustion engine will always generate heat while it is running.
* As usual it's not as simple as that, while an electric car is moving the heating system can draw heat from the components so there is some energy for 'free' here.
The main problem with that article is that when we get to a point when the majority of cars are electric, the ranges will be at least as large as ICE vehicles so running out of battery in the snow will be comparable to running out of petrol.