I think it has been put up by someone who knows that gender neutral sounds too nice. They want people to understand what many of us on here already do: gender neutral really means mixed sex. And to understand that mixed sex toilets are not safe for children (or women). Maybe they were forced to open a mixed sex toilet and really disagree, so this is their way of making it known to customers that it's not always safe for men to be in there with children.
They are showing their true GC colours! Good on them! I always point out to anyone who mentions gender neutral toilets/changing etc that in reality it is mixed sex.