Bit late in the day but a couple of points in relation to earlier discussions.
Regulation 261 refers to all flights out of EU airports, and flights by EU carriers into EU airports.
Re priorities for repatriation, I believe a trick was missed. As well as care and assistance, the EU rules require financial compensation (€600 for longhaul) to be paid for bumped passengers. If airlines could have received assurances from their governments that these sums would be reimbursed, they could have rung around their locally booked passengers on the resumed flights asking if they would voluntarily delay their journey by a day or two in return for the statutory compensation. I'm sure very many of them would have been very happy to take the money and give up their seat.