I don’t the in and outs of the case I heard – and from your suggestion there have been other similar ploys. So it is only 1 possible reason why LP has seen and heard about what he mentions. There could be other reasons – or it could be totally legitimate. To me it does sound like there is a snag somewhere and I’d be super cautious (from my expierience and view of the industry).
Another explanation (again dodgy) is that they are somehow selling AD90 tickets (effectively staff fares with 90% off the published fare) or AD75’s. I am not an expert on these so don’t even know if they sell them for First Class cabins. But that could also possibly explain a downgrade to club (as these get moved first if flight is full). It would also explain why no frequent mileage miles are earned and why dates might move last minute.