My eldest son (23) identifies as a cat. He is autistic and he has serious mental health issues, but his cat-persona is something very positive.
Cats are his area of special interest and they are also a great coping mechanism for him (what could be more calming than spending time with a cat, or learning to relax as totally as a cat).
He wants to work with cats, and already has secured voluntary work as a cat socialiser with a leading animal charity. So his interest is providing access to employability skills
He claims that he can communicate telepathically with the cats and they communicate in the same way to him. Whilst we accept this may be something to do with his MH issues, the communication is always positive and he refers to his 'spirit animals' as cats. Even though this experience is a little different from ours, we accept it and the guidance is positive. We would be worried if he claimed the spirit cats told him to do awful things, but they don't.
He is verbal and very articulate and he has given himself a cat-like name. With guidance from his support team, he knows when to use his cat name, and he has stopped referring publicly to the toilet as the 'litter tray' and his bed as the 'cat basket'. He may say these things privately to close friends and family, but he does not use these terms in that context publicly.
He has made a lot of acquaintances in gentle environments such as cat cafes, with people who are also fascinated by cats.
He has invented a whole taxonomy for talking about cat colours, ages and genders. It is very complex, but it makes use of his systemising skills. He used to be interested in meteorology and knew the names of every cloud type etc.
Oh, and he rides a motorbike, has a beard (which he identifies as 'whiskers') and has cat stickers all over his bike. Jackson Galaxy is one of his old idols
I think what I am trying to say, through these examples, is that once we accept difference, we can see how incredibly complex human beings are, and how incredibly interesting we are. I think the school are doing exactly the right thing by letting the young boy embrace his identity. They well be able to reach and guide him this way. It is a fantastic means of expression.