Even if her engines were operational, she would need a crew, including officers, deckhands and engine room to operate. A tug has a much smaller crew.
Also the ship had been laid up a long time and was out of class-no certificates, etc., so she would not be allowed to leave port on her own without considerable expense.
She is a large piece of industrial waste, and not worth much to anyone except the scrap dealer. Why risk life to save her?