I would not put your 9lb Yorkie rescue in a crate that small for any length of time. Has this woman been working on house training him? Puppy mill dogs are kept in small cages all their lives so they are accustomed to pottying in their cage. He has been trained to pee and poo in a cage so putting him in the crate is not going to work as an aid to potty training.
Have you ever taken care of a puppy mill dog? If you haven't you may need to have some help. Here is a link to a YT article about rehabbing a puppy mill dog although it is not all inclusive it is a start.
http://www.yorkietalk.com/forums/gen...nt-advice.html
Remember that all dogs are individuals. You will need to get to know this poor guy and find out what his needs are.