I think it's a complicated issue.
I'm not sure I would have felt comfortable sharing a changing room with a transgender boy when I was a child.
I think you can be sensitive to the needs of one child without making the others uncomfortable. Perhaps the school policy should reflect that, something like allowing transgender kids to dress and identify how they choose, but giving them access to the teachers restroom to use and a private space to change.
True...children have a different perspective of gender issues than us adults do though...why not ask the children themselves how they think and feel about it? I can bet they do not even think about that.
Our minds and emotions have evolved and revolved around what WE were brought up to be, not only by our parents or guardians, but by the society in which we lived those years in as well...as it goes down the line into the past with other's of various ages of adulthood...surely our ways are set by the time we reach senior citizenship.
But, we are talking about children of gradeschool age who most think about dolls, tv, gaming and homework...not whether or not a "transgendered" boy should be walking into the girls bathroom...and really...if we all can just stop and think about that a moment, most of us would realize that if we allowed the "transgendered" boy to go to the girls restroom, we would be saving him from the torment and bullying by other boys who most likely would try to harm him in any way, shape or form, physically.
There's enough deaths by suicide of teen and pre -teen gays, lesbians and the transgendered over being bullied...it's become an epedemic...it needs to end.