I don't understand how anyone could have a problem with this request.
1. This is modeling, if you can't show your face to someone to get some professional work, then
2. I'm a photographer, not a jackass that posts pictures of random clothed people on my website... to do what, sell them? I don't know of any ways to sell photos of random clothed people, but if they know of any... why don't they tell me???
3. Anyone serious about this business isn't going to be "afraid" of sending their OH SO PRECIOUS picture to a photographer before I invite them to my studio.