I am betting that the age restriction has something to do with insurance liability on behalf of BSA because the 16-hour course is supposed to have some type of "primitive camping" aspects (digging cat holes).
My son earned his First Class Rank at the end of March and he has not been put in a POR because there are no PORs available. Furthermore, my son has yet to be assigned a Patrol. Two options are available here: (1) My son can ask the SPL to appoint him as the Troop LNT Instructor or (2) A Scout may ask the SM for a SM assigned Leadership Project to help the troop. My son asked for option 2. The SM said that he could not think of anything at that moment but to contact him in a few days and also think of some project possibilities. My son and I researched some ideas and my son presented his ideas and the SM chose the Unit Hornaday Award. My son is not just a "HP helper"
. It is my son's responsibility to come up with a project that will earn the Troop a Unit Hornaday Award, get approval, get 60% of his Troop to participate in the completion of the project, fill out the paperwork for the Award, acquire the necessary signatures, and submit the paperwork. Keep in mind that a Hornaday Project is the same as an Eagle Project with stricter requirements (and Hornaday Projects can benefit BSA property).
The LNT Instructor is responsible for teaching the Scouts LNT skills and ensure that the Troop is utilitilizing the principles of LNT during outdoor activities. The Trainer Course does allow a Scout to teach LNT 101 (LNT Awareness) which according to LNT should take 30 minutes to go over all 7 principles. Should Troops allow the LNT Instructor/Trainer to present the 7 principles to the entire Troop during one meeting or during a campout? My answer and opinion is no. I believe that the intent for a LNT Instructor/Trainer is to present each principle over time (either weekly, bi-weekly, or monthly; pick one principle per month then plan a 5-10 minute activity for each meeting) and to observe Scouts during outdoor activities to ensure that each Scout is adhering to LNT principles. A good LNT Instructor/Trainer will include "hands-on" activities to illustrate why people should follow LNT principles (games, skits, songs, etc) and also maybe implement an AAR (After Action Review) for outdoor activities.