OP, he is YOUR first grader so YOU get to decide. Don't worry about this argument, it happens over and over and over on these boards. Have a happy trip!
I agree that the first grade boy is the OP's child and that she has the right to make decisions for what she thinks she needs to do to protect him, but why do her wishes and rights trump the wishes and rights of the rest of us? Why are we supposed to be happy with a unisex restroom, at the expense of the modesty and feelings of little girls, so the OP can usurp our rights for her preference? I'm a 64 year-old woman, and I really don't care if a 7 year-old boy is in the restroom with me. If I were a young girl or the mother of a young girl, I would care. I'm still waiting to read the cutoff age for bringing boys into the laidies' room. If a paranoid mother of a 15 year-old makes the decision that she wants to protect her son by bringing him into the ladies' room, is that okay? I recently was in a ladies' room while on vacation, but not at DW. When I came out of my stall, there was a boy taller than I am standing in the middle of the room. He was at least 14-15 years old, and I admit that I did a double take. He probably was a special needs child, but I didn't see a mother or anyone with him. Imagine a young girl walking out of a stall and seeing him standing there. For all I know, he could have been a sexual deviant waiting to molest little girls or adult women, for that matter. Since the restroom was full of people, he wouldn't have had the opportunity to molest anyone, if that were his intention, but maybe he just enjoys seeing girls in the restroom. He should not have been there regardless of the reason or the fact that it was his mother's decision, I assume. I've been in unisex restrooms in Europe, and I don't have a problem with them, but I don't expect to see males over the age of 3-4 in the ladies' room. The only rationale I can find in this argument is the mothers of boys are entitled to do as they wish and don't need to respect the rights of anyone but theirselves and their families. Sounds like sexual discrimination to me, and that's illegal.