Luckily no one was killed. NOLS has been around for a long time and has a good record of teaching outdoor skills, no one is perfect. I do know that they do not believe in firearms and apparently bear spray is not something they condone either.
Overall, I hope the teens get well and get back to growing up. I am sure NOLS will look into how they run courses in bear areas in the future. Most Alaskans in the bush carry some form of bear protection, whether effective or not.