Well I would have to disagree Scott. I think it sound to base a view that a professional journalist has used the term "slanging match" correctly. I would think her editors would have thought so to? The Macmillan Dictionary defines it as "an argument in which people (not a person) insult each other." and Google " a prolonged exchange of insults." I am quite happy with the justification on which my inference has been drawn.
"And Uncle, how do you know that her involvement was not passive?" The answer is I don't know, but in reading Georgina Robinson's article she states "An in-flight slanging match" I think you could reasonably draw an inference that one party did not berate another whilst the other was passive.
The Cambridge on line dictionary defines a slanging match as "an argument in which both people use angry uncontrolled language and insult each other" if Georgina is right in using the term correctly then I think both parties on the face of it have a case to answer.
Vive le revolution!
What is the name of that coffee shoppe in Agen? :)