Possibly because comedy, farce and absurdism are closely related and it's a huge issue of the day where children are being taught feelings automatically overrule biology in schools, and natal women in sports and many other situations are being pushed down the ladder? Many comedians automatically go after whatever subject is the flavor of the day especially where farce is involved.
Possibly because there's a huge issue getting some police forces to pay attention to physical crime, yet some police forces are very keen to police women's speech? A goldmine for comedy writers.
In some cases possibly something to do with being painfully aware how certain convicted pedophiles (along with rapists) have been using 'new' trans status to hide their convictions, and being accused of libel for stating the truth?
It's neither libel nor slander when it's true, but twisting laws intended to protect trans people from hate crimes allows spurious claims that 'newname' person is being libeled if they're outed as having committed crimes against children under their old name.
I doubt most trans people want to be used in protecting pedophiles anymore than most gay men wanted to be used to protect them in the 70's when PIE attached themselves to gay rights.
I can't stand Father Ted so knew nothing about Graham Linehan until I did some looking deeper, But I can see why he in particular, might be a bit obsessive about that subject...
Most sensible people have little problem with simply 'a man wants to be known as she/her and transition.'