I think this is a very interesting, forward-thinking article that is much more radical than it first appears.
Behind the soothing 'let's try to get along' rhetoric, Ditum is suggesting ways that feminists can change the whole narrative around 'trans rights', now that self-ID is off the table.
And God knows, it desperately needs changing. We are stuck in a loop of shouting about whether 'trans women are women' and whether predators will exploit self-ID. Meanwhile, the whole edifice of what 'trans' is goes undiscussed. The fact that trans identity has very different etiologies in men and women, heterosexuals and homosexuals, boys and girls, is unknown to the vast majority of the public.
So we cannot have a proper discussion about what legal rights should pertain to trans identity, until these things are understood. And of course, the last thing the TRAs want is an open and honest discussion of these factors. Right now, most people basically believe the narrative that some people are 'born in the wrong body' and need medical treatment and social acceptance to alleviate this.
There must be open scientific investigation into the causes of dysphoria, which seem likely to be very different in a 45-year-old male and a 14-year-old female.
I see what you did there, Sarah 
Ditum is suggesting strategies for feminists to bring these discussion points out into the open. One major strategy she is pointing to is to stop focusing on the GRA and who should be allowed to legally change sex, and to start talking about other things, such as the sex and age disparities among different groups of 'trans', the long-term health effects of hormones on children, etc.
This will (she hopes) take some of the heat out of the debate, which will enable more people to pay attention to it and join in, as the sheer nastiness of the self-ID fight has put many people off engaging with it.
Of course, this nastiness was a deliberate strategy of the TRAs, and I've no doubt they'll apply it to ANYTHING that feminists do, but it might be harder for them to continue to do this if we frame our arguments in terms of health, science, etc, instead of warning about predatory men taking advantage of self-ID.
We often talk about 'trans people' as if they are a monolith, instead of making clear that the teenage girls presenting to gender clinics constitute a completely different population to the heterosexual men who identify as 'trans women'. Unfortunately, all the focus on men who identify as women, and whether men will take advantage of self ID laws, has left the conversation in a rut where the main question is whether 'trans people' constitute a 'threat'. Why ARE teenage girls with complex mental health problems being lumped under the same category as men with a paraphilia? Why are we referring to both groups as 'trans people' and talking about them as if their needs were the same?
Many Mumsnetters, including me, have posted that they think the GRA should be repealed (along with all laws worldwide that allow the legal fiction of 'sex change'). But we've never really discussed how to go about building support for that idea. In the current political climate, that feels like an impossible goal, and that is because although most people don't agree with self-ID, most people DO have a great deal of sympathy for trans-identified people. They think (not unreasonably) that their lives must be very hard, and they want to make things easier for them if possible. The trans movement is saying: 'this is what we need to make our lives easier'. It's a very simple message and no wonder many people accept it unquestioningly.
And to a lot of the public, it looks like feminists are saying, 'no, we don't want to make the lives of this group of people with significant vulnerabilities easier, we are going to keep repeating that humans can't change sex, etc.' This point is where gender-critical feminists appear out of step with public opinion. Not on whether you can actually change sex or not - everyone knows you can't.
What Ditum is saying is that we should start to question whether the TRA demands are genuinely going to help trans-identified people to comfortably exist within society. I know it seems an anathema to focus on 'trans' instead of women, but that is only true if you are equating 'trans' with men. 'Trans' includes women, it includes children, and especially increasing numbers of girls. These 'trans' people are indeed our priority, as much as all other women and girls, and it is right that we should be asking whether the current trans movement and its demands really serve their welfare.
Asking these kinds of questions takes the narrative out of TRA hands, allows for the debunking of certain propaganda, puts pressure on the medical industry to rein in the paediatric gender docs, and opens up the discussion to include the factors that are really driving the gender identity phenomenon, all of which are needed if we want to shift the momentum and change the cultural direction around 'trans'.