Is it really just a ballroom? I see few people mentioning the East Wing was actually covering the White House's underground bunker. Maybe Trump wants a more future-proof nuclear refugee.

Maybe I’m mistaken but I thought I had read somewhere that nukes are now so powerful that bunkers don’t really work, even Cheyanne Mountain not considered safe anymore. If so, not sure if that’s a possible upgrade.

They can gate to the alpha site if the danger is serious enough.