They are trying to save top weight. Galvanic corrosion is well understood and sacificial diods are necessary. This is done in pleasure yachts. I think the brits did it on type 42’s. But again they are virtually unarmored. Is that smart for a warship that is expected to dogfight with smaller craft and take on shore batteries?
Yea, yea, I know why they’re going down this dead-end road.
The fact remains that aluminum expands roughly three times as much as steel due to temperature changes.
And that means that stuff’s going to fail long before anyone takes a poke at the ship with a ballistic weapon.