The way I'm reading it, it isn't actually an LGBT school, its a school for people who have various non behavioural problems which makes intergrating into and learning at mainstream schools difficult. Its not deliberately segregating anyone, as from what I understand, its there for those whom normal school doesn't work for, its offering them the chance to have the education they deserve and their needs understood. Plenty of people move schools due to bullying, for whatever reason, I imagine having somewhere to go where that isn't going to be an issue, especially if the bullying has affected your education, as it will mean its probably a better place to catch up.
I also don't think it will necessarily detract from schools dealing with the issue of homophobia either, a school like this is unlikely to be a place you initially choose to go to. Most kids do want to fit in with the rest of their peers, its also probably not going to have loads of places available, so its really in the schools interest to deal with the main issue of bullying before getting to this stage. But for some people, even if bullying has been dealt with, a fresh start is whats needed.
Its also great that a place for young carers, people with mental health issues and young parents, though I think there should be equal focus, rather than the school being designed for LGBT youth. Thats really my main bug bear with this.