Isn’t it the other way around? Aluminium has a lower reduction potential than iron, so the aluminium should be the first to go. Even lower than zinc, which uses the same mechanism in sacrificial anodes and galvanisation.

I once had the idea of attaching “sacrificing cathodes” made of iron to aluminium beverage cans to make them go away faster when discarded in the environment, but that just causes more problems than it solves, so it’s better stick with container deposit schemes.