He was pulling 12v from the 12v battery, but the car was topping up that battery from the main power pack. So he was effectively drawing power from the main pack. This would impact more than the 12v battery. I doubt tesla ever anticipated the 12v battery being discharged so quickly/continuously. They probably just don't know how this might impact any number of systems. An overheating 12v charging/rectifier system could fry something totally unrelated. This is exactly the sort of situation where a warranty for the entire car could/should be voided.
That LA battery is there for a reason. I don’t work with Tesla, but I would assume it is there as a backup for the monitoring and safety systems. There is a reason they are using an LA battery in a lithium powered car.
Obviously there are things that should still be covered, but there is more potential for harm here than just to the 12V battery itself.
Anyway the Tesla doesn't generate power during driving like a regular car does, so the 12V power is always topped up from the main Lithium battery and the DC-DC converter needs to be reasonably sized to accommodate eg. 600W supply. If power was taken from the regular port than i would count it as regular use (eg. when camping i would count on my car to charge things, even if it uses fuel and generates 0 km/miles.)
What if you keep jump starting another car with leads directly attached until the LA battery is depleted? That is a very common scenario and Tesla should size the electronics correctly or make it resilient for that use.
It’s also clearly stated on the owner manuals.
It's hard to tell because this article is pretty terrible. It depends on what they mean by "voids warranty". If Tesla just won't replace the 12v battery for free because he deep-cycled it out side of the intended use, that seems pretty reasonable to me. If Tesla tries to use this as an argument against replacing any other part of the car (including the main battery), I think that's pretty clearly a violation of the Magnusson-Moss Warranty act. IANAL.