guess the best way to find out who made the planning error would be for you to ask your Ops whether Astraeus Ops requested the change the night before (!).
Get your own ship in order before pointing fingers.
I would suggest that Aer Lingus Ops declined the change on the basis that they wanted to highlight to their management the inadequacy of the operation.
Does anyone really worry if EI go under?
No one apart from it's shareholders and those with future bookings with the company. That said, any company going under dosen't really worry anyone not connected with it, does it? It's the same in all industries in life.