Maybe that's just a bug
In human laguage, this would mean, you're not going to use a battleship when a small fishing ship suffice in order to perform some task.
Unless you're trying to impress your girlfriend.
You:mate in 1?
Computer:find a better move
You: slowly take all his pieces,promote 5 more queens and arrange all pieces back to starting position and checkmate with discover attack with king?
Computer: perfection
Maybe that's just a bug