Our brother-in-law does Schutzhund with his German Shepherd and when we visit he asks us to ignore the dog and not pet it. We are dog lovers and it feels wrong for me to treat the dog as though I don't want to pet it. What is your opinion on how we should treat this dog?

Our brother-in-law does Schutzhund training with his 2 year old GSD. The dog lives in the home with the family which has 6 and 8 year old children. The dog and the other family dog live in the house, sleep with the mother and father and plays normally with the children and the other dog. When we visit we are asked not to pet the GSD. The dog wants to be pet by us and repeatedly comes for attention only to be growled at by the owner because when she is pet by us she pees. His opinion is that we should completely ignore the dog. The only problem is that we are dog lovers and the children are all over us as we are their aunt and uncle. It feels wrong for me to treat the dog as though I don't want to pet it and then expect the dog to allow the young children to be all over us. What is your opinion of how we the visitors should treat the female GSD?