Then Pets to me are a method of life extension and need to be lumped into the other things that are already banned. If any of you have started and have pets get rid of them. If you have used this trick, then start your file over since this is a late changing rule.
That would take quiet some of the fun out of the challenge.
People could really just click it away if it should happen, or immediately move out the sim if it gets resurrected, or even delete that particulary sim totally in that case.
Else it should just be a part of the strategy if you want to risk having a pet that extends the life of a dying sim, and there by ends you challenge right there, or you rather play save without the pets.
That's my thoughts at least.