Are Breathalyzers accurate?

So basically, my leadership is trying to getmy buddy 'busted' for underage drinking, which is far from the truth. I'm in Korea, and some buddies wanted to get out and see the country, after a long night of shops, clubs, hiking, restaurants we showed back on post, keep in mind were all over the age of 21 except my friend, we notice a bigger group, that seemed like they were definetly drinking, so we let them go through the gate to check ID cards to get on post. Out of 8 personnel, 5 got pulled to the side and we went through, and my buddy was another one that got pulled to the side, my guess is because they were under the age of 21, and just doing his duty at the time. The NCO on duty conducted a breathalyzer test on all 6 personnel, my friend being last. One after another, some a few times because they weren't doing it correctly, I made sure my friend did not consume alcohol, I was the good battle buddy I guess, and after hearing "there's a hint of alcohol so standfast", I was confused. I KNOW he did not consume any alcohol. He told me the 1sg recommended to the PLTN SGT to give him a counseling, and they're pushing for an art 15 without substantial proof, no paperwork was done, the MPs were not called, the commander did not give permission for MP to come, and the NCO on duty was not an MP. Is it allowed to just charge soldiers off word of an NCO, without any liable proof? I'm not 100% sure but I thought only MPs can administer Breathalyzers to suspected personnel under the influence, not even the Medics. Is it worth him fighting this or will it cause more problems For him? He's a SPC, and definetly would be bad to be knocked down to a fuzzy for something he had no control over.