Why do unused Refrigerator Appliances Grow Mold, while unused Cabinets and electronics don't?
They don't mean "Even when unplugged".  They mean "When unplugged". 

Because refrigerators are wet inside, and refrigerator doors seal too well

Try putting 1/2 cup of water inside a cabinet, then bagging the outside of the cabinet door with plastic. You'll get mold inside that too.  

The interior shell is not a hermetic seal.  It's just some cosmetic cowlings because white plastic is more attractive than galvanized metal and insulation fiber.  Moist air still moves around and through it, then condenses or freezes. 

It's water in all those inaccessible spaces that is the problem.  

After some number of months, that will eventually dry out.  And then, you can let the door close.