These are the three conditions that Apple says may lead to throttling: battery with low charge, cold battery, or old battery. All three of those are specific to the limitations of lithium ion batteries, not to Apple or their designs. All three of those are scientifically known to reduce total voltage available to the system and thus potentially limit the amount of current that can be supplied to the CPU for a given task. Not enough current to cover the task = shutdown...that is, without an additional power management control like Apple has added.
Synopsis: easy to prove that the issue Apple was addressing exists within lithium ion battery technology. No question that Apple can roll out endless amounts of scientific proof to that end. The question is whether or not it's going to be effective to argue in court that the phone shutting down and being non-functional is to the advantage of the consumer vs. keeping it functional yet slower. That's what it boils down to...and it doesn't sound like a very good argument.
Either way it is a design flaw, that needed corrected with a "power management" update over year since phone was released. Should have been provided from the day the phone was released. None of those high paid design engineers thought of this when designing the chip/phones??? Makes me think something else is going on, this isn't new science.