@SwissGemma 'Notmyname the issue is that with guides we are talking about children who have no choice but to self id they are in the starts of finding their identity. At this point they may well be Ellie - as I suspect the majority if trans people are.'
My apologies Swiss, I did/do have some thoughts (obviously!) vis the GG issue per se but felt the broader issue was A: worth remarking upon for some broader context here; & B: I'm struggling with ADHD here which in turn means I struggle to be succinct, hence post was already very long[embarrassed] That said, I'll try and write those GG specific thoughts here:
1: IIRC we are talking about children aged 10-14 yes? I feel that children that age who are questioning and exploring their sexuality and sense of self should be supported in that and not have their feelings being superimposed upon by what feels like a very very aggressive Trans ideology right now. I say that as a DM to a now 27 year old living happily in the LGBT community and finally at peace with their sense of self. So at a headline level, it concerns me that children are being pushed to 'label' themselves as something way way before their feelings/hormones/sense of self has levelled out.
2: If however we park the above and accept that kids that young can genuinely self ID it seems that current GG policy is itself exclusionary (oh the bloody irony huh?) - namely exclusionary of those born with a vagina.. 'managing them out'. I can't agree with that.
3: In terms of 'inclusionary', I also can't agree that meeting the 'rights' of a tiny minority remotely justifies trampling on the rights of the millions. As it won't be a pollyanna like scenario in which (say) a Muslim girl can negotiate her sleeping arrangements as she won't be there anymore as her parents will either have removed her or not let her go in the first place if they believe a male bodied child will or could be there. THAT is the reality here.
4: It feels like we are being told that those who possess a penis (all of my DC have or have had a penis, patently I'm not coming at this from some 'anti-male' position but rather the protection of the rights of those who are girls and need girls only spaces) have rights which trump those who don't. IE The swathes of girls who won't be allowed to go for religious reasons, girls in foster care, survivors of abuse - they are ALL having something taken away from them in favour of the tiny minority who happen to have penises. That frightens me, as does the slamming down of any discussion of the (many) repercussions of it.
5: The safeguarding issue is just being swept under the carpet. It is naive in the extreme to believe that predatory behaviour suddenly only kicks in at 16. It is horrific to think of any child aged 10-14 committing sexual assault but it happens. It's wilful ignorance (IMO) to just wish that reality away and instead just wait for the first RL assault to occur 

6: Lastly, how can parents give informed consent when they are not informed? Male leaders not transitioned but just self ID'd have no place in a group where their mere presence will both alienate groups of girls who arguably need the safe space of GG the most (see 4 above) and potentially pose safeguarding issues. It is cray cray that simply saying 'I'm not Bob anymore, I'm Bobbie'** suddenly erodes years of safeguarding practice.
**To be absolutely clear, I'm not talking about people like Ellie who have fully transitioned and no longer possess male genitalia. With the normal safeguards in place I can't see why she couldn't or shouldn't be a leader. With quite hefty RL experience, I can say I have never known a single fully transitioned woman that I would personally have any innate fears around (although I appreciate others may not share that view) - I'm talking about those who simply self ID as that is where the patently obvious risks and costs lie.