I suspect the angle the barrister is going for is that “Adult Human Female” is a dog whistle, which he defines as a known signal, a phrase with a specific meaning to those “in the know”.
He would therefore try to claim that the film’s title is a way of aiming it directly at those who are already GC, as that’s how they’d know what the film’s title meant and implied. This - together with there not being any opposing voices/opinions* - means that it’s a piece of propaganda rather than a genuine academic endeavour, and designed to reinforce an already accepted viewpoint rather than stimulate debate.
(* yesterday’s witness did debunk this by explaining why there were no dissenting voices.)
Therefore, he will try to say it wasn’t a legitimate film created in good faith to debate a point, but instead it was always designed to be a harmful, one-sided agitprop piece aimed at sympathisers of an ideology that targets trans people, and UCU were right to oppose it to prevent the harm.
Then there are the attempts to say it’s not a piece of academic work because not all of the people interviewed were academics (which is a nonsense, as @Kucinghitam demonstrated) or that it’s not a proper piece of academic work because statistics weren’t precisely cited (which is also nonsense, it’s a film aimed at a wide audience, not a paper submitted to a journal). Thus undermining its legitimacy.
I think those arguments are bollocks. I don’t think it will fly because the judge has already stamped down quite hard on the dog whistle issue and I should imagine Cunningham will drive a coach and horses through what’s left of the defence argument. But IANAL!