I'm not sure what the regulation says, but for someone with Plat status I would bet that AF/KL will pay for the meal during transit.

I did not have exactly this situation, but I was rerouted from LHR-CDG-TLS to LHR-TLS direct because of the LHR-CDG being cancelled. The BA flight arrived in TLS roughly at the same time as our original itinerary, although obviously the departure from London was much later. AF paid without issue meals+alcohol (~90 GBP) for the 3 pax on the booking (2 plats, 1 statusless) since obviously we had no access to a lounge in the LHR terminal served by BA. (And they also paid the full cancellation compensation )

As usual when making the request, it's best to be as factual as possible, little emotion, not too many details. That reduces the scope for misunderstanding/confusion/risk of being denied.