I'm considered overweight and even obese by some standards at 6'1" and 210lbs. I am actually in good health. I see the biggest problem here as lack of skill. She may have been new and nervous, but she probably has the knowledge and is just unable to display it properly with a class. She is also unskilled at handling her weight. I know many overweight divers who are comfortable with it and can do all the skills needed. Maybe she recently put on the weight, had a surgery, had an injury, or had a baby, maybe still pregnant(not a good idea to be diving). Whatever it is she's not comfortable with her size yet, and that mixed with being a new instructor just didn't go well. I agree with many of the posts above that she needs a bit of help before she is left on her own with a class, but that's what the LDS should do by recognizing it and keeping her with other instructors until she can do the job.