DFC
If you only consider the facts given prominance by the AAIB in the report, then you would come to that conclusion.
There are other factors that have been dismissed or overlooked that, when integrated with the AAIB's own scientific data, support an entirely different outcome.
Your views on microlighters are unfounded and, I suspect, urban myth. Just as some GA pilots have done, I am sure, if you look hard enough, you will find a microlighter that has fitted a GPS without sending in a mod form. You cannot totally dismiss a system because a few rogues who decide to ignore it.
Your suggestion that a school have not reported a fault for fear of having a fleet grounded is, I believe, pure fantasy. If I am wrong, then it is your duty to report the matter to the CAA and I would urge you to do so today. Once you have done so, perhaps you can tell us the details.