It sounds like me like the FA decided that 1A / 1C is an "emergency exit row", even though it probably isn't on a standard IB configuration with Business Class. It's worth noting that many LCCs in Europe don't have a bulkhead / separator on the left hand side, so 1A - 1C truly are in an emergency exit row.

As always, you could escalate the situation and potentially get kicked off the plane, or you can just grumble and move seats. I doubt that you will find a written policy about row 1 because of the different ways short haul Airbuses can be configured.