I think it is also important for a scenario like this that as well as acknowledging that mental health should be cared for - there is also an opportunity to reassure... men don't tend to experience any form of violence from men in the loos - so no need for a man pretending to be a women to feel unsafe in the men's loos - no-one is interested, they can come in and pee and leave and even wearing the most 'outrageous' of women's outfits there is unlikely to be any comment...
If there were a strong belief that men cause violence to women in loos and this was a reason for 'trans women' who are now 'women' (so they argue) to avoid going into the men's loos in case of violence against them - then that strong belief would apply even more to men going into women's loos - and thus the trans community would have to admit that a 'trans woman' (i.e. man) in a women's space is far from ideal
so the trans community is confused - they can't argue strongly that they are in danger in men's loo's as it simply supports the argument of women against them being in women's spaces...
but equally it is difficult for them to argue no danger, because then there is no reason to go into the women's loos - the men's loos will be fine!
and to argue the truth that they want to be in women's spaces as men to validate their charade / or for more nefarious reasons is of course the truth that can not be spoken.
tough logic call for them - all because there is no underlying logic to a man claiming to be a woman!
the reality of course is that there is risk when men are in women's spaces which is why a 'trans woman' (man) should not be in women's loos (risk for the women) and has no issue being in men's loos (no risk as man in man's space)
wow there is a bit of a headache in all of that - much simpler of course to go back to men with men and women with women!
so, back to this lad - it is worth reassuring him that as he will clearly be seen as a bloke, whatever he wears - he will have no issues in the men's loos!