I still feel like that argument is like a "won't somebody please think of the children" one.
If app stores need to be locked down to protect the elderly, then surely the Internet needs to be locked down to protect all children. After all, Safari still navigates little Jimmy to pornhub if he clicks the link.
I feel like the real solution, same as the one most parents should be using instead of forcing it into everyone else is the same it's always been; don't give young Jimmy unfettered access to the Internet (and use a child/safety filter in your own home/on your own devices) and for Apple to provide a setting that enables/disables alternative app stores, so that children of the elderly can choose for them in the same way they'd choose for their children.
In fact, Apple devices already ship with something called "Assistive Access", which is a mode that you can enable that limits what can be done with the phone. In particular, it limits the ability to install apps.
If app stores need to be locked down to protect the elderly, then surely the Internet needs to be locked down to protect all children. After all, Safari still navigates little Jimmy to pornhub if he clicks the link.
I feel like the real solution, same as the one most parents should be using instead of forcing it into everyone else is the same it's always been; don't give young Jimmy unfettered access to the Internet (and use a child/safety filter in your own home/on your own devices) and for Apple to provide a setting that enables/disables alternative app stores, so that children of the elderly can choose for them in the same way they'd choose for their children.