I wouldn't get too excited about this as Andrew Gilligan isn't exactly a feminist being better known for his campaigning as a macho lycra clad cycling czar.
But even having a right wing trans questioner in No 10 could be interesting way of getting gender critical views into the inner circle.
What it also shows (and there was a really good article about this whose link I have lost) written by a journalist owning up that they, the press, treated Boris much more leniently and admiringly because he is a journalist and so have never really done a hatchet job on him, like they all ganged up to do on Theresa May (who is you remember took up the impossible job when Boris ran away).
So in America with have government by reality show and now in the UK we have government by Fleet Street (eg Boris giving Osborne's policies priority, who is / was his editor).
Unfotunately I think this will mean a lot of media coverage of Boris will now not be about pure reporting but about old media infighting using the real issues of everybodies daily lifes to score points off each other.
Sorry to say link is Pink News, but they are so diligent in tracking trans issues they often are first with info like this. www.pinknews.co.uk/2019/07/31/boris-johnson-appoints-anti-trans-rights-journalist-as-downing-street-advisor/