Automatic cut mains power on a thunderstorm
You don't unplug electrical equipment to protect it from a direct lightning strike. You unplug it to raise its damage threshhold, to increase the likelyhood of its surviving a nearby strike. As such, opening any contactor or relay would be beneficial.

I live in one of a row of houses. A few years ago, another house in the row was struck by lightning. Let's call this house zero. They lost all their electrical equipment, and had to be rewired. House one next door lost all their electrical equipment. House two lost only electronic equipment, simple electricals with motors and dumb switches still worked. In house three, I lost my ADSL. House four survived with no damage.

So there's plenty of scope for a small break in the wiring to reduce the scope of your loss with a close, but not direct, strike.