*Women and children firmly relegated to the play area and men gathered on the green area, males from about 11 or 12, up to men in their 60s.
The men had colonised a section of a public park and you don't regard that as worrying?*
I think it does sound worrying, yes, although it may simply have been that the men wanted to play football and the women didn't. That's what would have happened in my (heathen) family - none of the women are interested in football, and some of the men are. More importantly for this thread, though, I also think that this is yet another example of two wrongs not making a right - a 'straw man' argument if you prefer.
The issue of the freedoms of Muslim women are separate from issues of trans rights, although they have fallen under the same E&D umbrella.
Remember that not all Muslim women separate from men because of an oppressive husband/father/imam. I have friends who see it as liberating to cover their hair and to maintain a distance from men, and they do this with differing levels of strictness, sometimes based on their own judgement of the situation. As older women, I am pretty sure that none of them would be comfortable undressing behind a curtain when an extravert young person with a male body was on the other side. Not necessarily because of their faith, but because they would feel uncomfortable. I used to shop in Monsoon a lot, in the days when I could make a decent fist at setting off their clothes. The three branches I used regularly (a city centre one near my work, a small town one near my house, and a larger town one near my sister's) all had a curtained off area just off the main store as a changing room. The assistant would, if the shop was busy enough, stand by the curtains and let you in with your clothes, checking if there were a free 'cubicle' inside. The 'cubicles' were also just curtained areas, all of which opened onto a sort of corridor where sisters and friends could sit, and hand you clothes as you tried them on. There was very little privacy, as you had to open the curtain to do this, but the atmosphere was relaxed, as there were only women in there.
As a non-binary male, Charlie may have had a beard/stubble, very 'masculine' dress, a swagger and a deep voice, and entered the changing area 'presenting as' a man. He may not, of course, but as this was very clearly a publicity stunt, there is a good chance that this is the case - the shop assistant told Charlie that 'men' weren't allowed in there. It doesn't sound as though any attempt had been made to minimise any signifiers of masculinity.
Of course Twitter is media - it is one of the most effective ways of drawing attention to a cause - and the more I learn about this case the more I am certain that this was an orchestrated publicity stunt from the start.
All the non-binary young people I've known (several, over the years, including the child of a close friend) are shy, socially awkward types who would hate to draw attention to themselves in this way. Not a representative sample, agreed, but social anxiety and so-called 'gender neutrality' do appear to be linked.