According to the clarifications posted by Commission on EC261 it seems SN are on the hook for Duty of Care due to SN totally shutting down.
I’m thinking the best option would be weekly invoices for the costs incurred for stranded pax, that way, there might be a chance it might get paid before Carsten decides a liquidation action is in order.
There are a number of pax stuck abroad, who cannot leave by any means except maybe private and government repatriation flights.