Kyle writes:

Is there a better way to get rid of rust on cast iron?

Acid. Pool acid, CLR, Bar Keepers Friend.

You can't win with corrosion on outdoor grills. First you bake it bone dry
and apply chloride ions (table salt). Then you let it cool and moisten it
with a nightly condensing atmosphere. It eats aluminum, cast iron, steel,
stainless, everything. The military should use it as a test specification.