What would happen if you had removed the photo but continued to run the site, without using the photo. Then the only issue is the "back-pay". Seems like their

What would happen if you had removed the photo but continued to run the site, without using the photo. Then the only issue is the "back-pay". Seems like their argument for "back-pay" is weak if you were previously under a good faith belief that you had permission to use the photo.