Obviously I think its great that there's this third choice (because that would be my preferred tickybox), but if that box is labelled "transgender" that kind of raises questions. What about people for whom the binary choices are correct, but who have trans history or are currently in a transitional stage? Would they feel excluded, or potentially "lumped in" with a group they feel they don't belong to?
The inclusion of a third box also implies a recognition by the schools that other genders besides the binary exist, and that's good. But how far does that recognition go? Will there be sensitivity training for staff? Will there be support for students? What about unisex facilities? What measures are in place to deal with harrassment? It's all very well encouraging non cisgendered people to enrol, but if these young people are not going to be given adequate help and support they might simply be harrassed off their courses.