William,
Just keep in mind that there is a difference between being absolutely honest and forthcoming about potential barriers and suggesting to them that they are being unrealistic. The latter implies a judgment on your part that, simply because of your position of power and authority in those conversations, amounts to restrictive career counselor -- something that is expressly prohibited under the law. Never be afraid to state the facts of the situation, but leave the conclusions to the student!
Dr. Jane Jarrow