I think this shows how dangerous all this is. You’ve acknowledged that if this man wasn’t claiming to be a special kind of “woman” man, you would have much stronger boundaries, and be able to see clearly how inappropriate his behaviour was.
You wouldn’t be “a bit annoyed” (which was the only way in which I thought you were being unreasonable - for under-reacting), you’d be “plain livid”.
But because this man is claiming to be a woman, the usual rules don’t apply to him. And it’s hampering your ability to safeguard your child/other children.
This man was talking to your DD as if they were peers, rather than unrelated adult and child: at the very least, that’s a denial of the power differential between adults and children, and an unawareness of the responsibility of adults to behave in an appropriate way around kids, because of that power differential.
Which is a safeguarding risk in itself.
Clearly we can’t know his motivation, but as you’ve recognised, he may have AGP, in which case he was performing his fetish in the presence of your child, and at worst, he’s a man who gets a sexual kick out of talking about his male genitalia to a female child. Which is obviously a much more serious safeguarding risk.
It is well-evidenced that men who enjoy cross-dressing are more likely than the average man to have other sexual paraphilias too; and yet we are living in a time where - despite our supposed focus on child safeguarding and issues of consent - we are expected to extend the benefit of the doubt to men who cross-dress in public more than to other men.
I realise that you are going to protect your child by not taking her to any more work events where he might be present, but I wonder whether your actions would be different if this were a man who doesn’t claim to be anything other than a man. I understand why you feel you can’t report this to HR given the culture of your company, but it would be good to think about whether you would if this was a man who didn’t claim a trans identity.
Because obviously if he’s being invited to “family friendly” work do’s, he’s potentially going to come into contact with other people’s children too. And you should be able to flag up this kind of behaviour as an issue, whereas it seems likely that the very most you’d be able to do would be quiet words with other parents, only the ones you think wouldn’t denounce you for “transphobia” of course.
And in this way we’ve moved back several decades: it’s like the times when sexual harassment in the workplace was ubiquitous and women’s only defence was telling each other to be careful of so and so, and try not to be alone with him etc.
Even though we’re now supposed to be living in a culture with vastly more awareness of safeguarding and protecting the vulnerable.
That’s what I mean by saying how dangerous this all is. It lowers boundaries, which increases risk. I’m sorry you’re having to deal with this.