If the loan does not go through for various reasons, in the purchasing agreement, you are responsible to pay fines per day pass the deadline. Which in that case, you probably will rather get another worse loan offer to avoid the penalty (2 bad apples to choose) and to get the house. You won’t have time to do another loan from outside and also in the agreement, you probably HAVE to use this broker in order to get the closing cost reimbursement. You got stuck with the guy’s loan in order to keep the closing cost reimbursement.
I would rather lower the offer price by 9000 and then do your independent loan search, forget about the closing cost request. Or , lower the closing cost coverage request a little as a counter offer.