Deborah,
You walk a very thin line here. Before you make assumptions about a student's ability to be hired, you need to consider the possibility of reasonable accommodation. There are also some sticky issues surround the development of technical standards. While reference to lifting 50 lbs may be the traditional way to state this requirement, it doesn't necessarily mean it is logical. Does that mean if the student lifts something that weighs 53 pounds, and drops it, it will be considered OK? I recognize that proprietary institutions that are evaluated (by accrediting bodies) on their placement rates face special challenges in dealing with students who seem unlikely to find employment in the field -- without unnecessarily restricting them on the basis of disability. My best suggestion is that you be flexible in your thinking, be open with the student, and make the best possible assessment of how realistic the student is about their limitations. The best you can do is the best you can do!
Dr. Jane Jarrow