As far as Possie goes: I have no clue how she died. Chris could've been negligent or fucking around and done something. In which case, there'd be nothing to defend: Chris would simply be guilty of being a shitty pet owner. Or it could've been something more mundane (ie some existing infection the cat brought in).
There is no way to do the following, but if somehow there can be a headcount of Possie's litter mates and how many of them died, it would help paint a picture of a cat's survivability with and without Chris.