"Would you refuse to protect a family member if they couldn't give you anything in return?"

Because that's what it comes down to, in the end. They will protect them as long as they can, even if they aren't able to produce or raise offspring anymore, which is the one practical use they have, simply because they are weaker. Greater efforts will be extended to ensure the continued survival of a wolf who cannot help with the offspring anymore than to keep alive a werewolf that cannot fight anymore. That's just how it is done, because wolves are weaker, and they are the core of the family, the place where the tribe is born from.