What differance of opinion ?
You don't work for CX, you work for KA.
Your COS is still with KA, and that had provisions in it that already compensated you for not working for an airline that can take you to your home port. Your COS never gave you boarding priority with CX.
The DPA push with the threat to go into contract compliance over something that is not in your contract is inexcusable. It has significant ramifications for CX employees.
I don't give a crap about travelling on KA and I have no sympathy for the CX staff who want to. CX staff don't work for KA, KA staff should have priority on their own airline, just like CX staff should have priority over every other airline when travelling on CX.