Ka. Boom,
Since when does someone have to be named? Any pilot within Qantas could check who the F.O. was, it is not hard for that information to be found, also as you would be well aware, the crew on the flight would also know who it was. For Libel to be proven in the legal context the person does not have to be named if it is reasonable to expect that people can ascertain who it is that is being referred to.
Regardless, In the context of the post I am not trying to point to the legal aspect of libel but the willingness of someone to 'slag off' another professional pilot for no good reason (name known by all or not!).