For me it comes down to what was the actual premise here for UKAD at the time? Was it to allow BC early NA warning or was it to actually help British Cycling further understand how/why one of their riders had a trace for NA? Clearly, UKAD doesn't appear to first suggest they'll run the study on behalf of British Cycling, which makes sense, the rider in question causing the concern to carry out such a study had no AAF, so there was no WADA requirement UKAD study the cause, they already know NA metabolites are naturally created in the body and why WADA sets a threshold for the lab to work with. They also know cases where NA from supplements have been proven in lab results and used in defence by athletes too. Equally, I'm not sure an NGB could subcontract their NADO to run a study into NA and supplements use and if they did, it still wouldn't look great headlined in Daily Mail effect.
If the premise was an early warning, the obvious question is why did UKAD only agree to this single metabolite to be studied? Why did they want it all be done through a WADA lab and surely if BC themselves wanted an early warning system, they don't send emails backwards and forwards between themselves, their NADO and a WADA-accredited lab. You would simply subcontract a private lab, take your urine to them and receive the results. Doping is always about evasion, not the inclusion of anti-doping in my opinion.