Stepping back a bit, I think the problem is that a lot of people are used to conventional engines and their separate mags. They are "safe" to fly on a flat battery, just so long as you can somehow get the engine started. Loads of people have done this, getting somebody to hand crank or start with a GPU.
Checklist or no checklist, I don't think people expect to have this rather odd failure mode. Also, a lot of pilots are used to flying without checklists - they jump in and fly. It's not right but it's an old tradition throughout GA. On an old C152 you get away with it. But people who rent these nice new machines will have to get their head in gear, and if the owner does even half decent vetting this is going to reduce the number of eligible pilots!
For some reason it's difficult to get a "two batteries with diodes" thing certified. It's such an obvious solution to electrical power issues but I know people have tried in (in the USA with a 337, usually) and gave up. It would be a great solution to a comms failure: feed the radio(s) via diodes and have a 2nd battery somewhere. 2 radios won't both fail together. Instead, one has to carry a handheld ICOM...