Sounds like a cabin crew with an axe to grind and there are literally thousands in BA.
Why go straight to the CAA? Why make a conspiracy theory like claim that records have been removed? Why go to the DM of all “newspapers”?
Sounds like it’s a character assassination of a pilot who stood up to a BA mainline purser for once in their life. Sad state of affairs. I hope the pilot involved sues the DM and the individual involved for libel/slander as appropriate.