This response is provided based on the information you shared and should not be used as the sole source for making a decision. You should seek guidance from the chain of command, IG, JAG or other certified agencies before making any decisions. How you chose to use this information is totally up to you and is your sole responsibility.
Exemption from training and duty rosters for this position at the discretion of unit leadership. There is no other regulatory guidance other than the duty roster regulation AR 220-45.
Also keep in mind unit leadership cannot exempt any Soldier from mandatory training directed by Department of Defense or Department of the Army.Hope this helps to some degree.