I would argue that, in this example, Flying Blue has done our intrepid traveller a huge favour ;-)

Besides - in the vast majority of such corner-cases involving last-minute requalification, I would imagine that the timing of these flights was chosen as deliberate ploy/strategy by an engaged frequent flyer. Now that this frequent flyer is aware of the "change" from physical to digital cards, and the consequent issue of a potential "gap" in status coverage, they can adapt to this new scenario and plan more appropriately. This could take the form of ensuring that requalification is locked in early enough to prevent the issue (and thereby also avoiding any unforeseen hiccups related to travel disruption or rerouting on crucial last-minute qualifying sectors); that the flights in the potential "problem" period are booked in business class (thereby having the perks of status included regardless of status), by avoiding travel on partner airlines which may introduce an unacceptable delay in posting at what is a critical end-of-year time; or by actively ensuring that the XPs for the flights just made are forced to post immediately to your account. (At least on KLM, doing an auto "retro-claim" immediately upon arrival at the destination airport always goes through immediately; I have not tried this on AF, as I have not flown AF in the past several years, but it has now become habit for me when travelling on KLM).

As engaged frequent flyers, we all know we need to engage with the programme/rules/opportunities and look out for our own interests; as such, it will be in most frequent flyer's ability to adapt their requalification strategy to negate this potential down-side.