The interview I posted, the author addresses that question:
SiN: Some reviewers are touting your book as YA. Was that what you had in mind when you wrote it?
MRP: Absolutely. I wanted to write a book that I would have enjoyed and that would have helped me to come to terms with my homosexuality when I was a teenager. There weren’t any books like that 25-30 years ago and the gay books that did exist back then, if I’d had access to them, would have embarrassed me and would have filled me with guilt, due to their very adult nature. If even one gay teen reads The Filly and feels better about himself because of it, I will feel that I have been a great success.
If the author actually conceived of the book as a novel for young adults, that may explain a lot about the impression I got on my browses through it, and it would alter my expectations when I actually sit down to read the whole thing. I had heard nothing about the book when I found it at Giovanni's Room, our independent gay bookstore, and just picked it up because it was a gay Western. While Giovanni's Room doesn't have a "young adult" section, it does have a section for books aimed at gay parents and at children growing up with gay parents, and so forth, but that wasn't where they had
The Filly. I found the book shelved with all the other gay novels, and I think that probably colored my expectations, too. I wasn't expecting a novel for "young adults"--and I had also recently completed
Longhorns, which is most definitely a novel for adults (had a good story line but struck me as a little simplistic and implausible).