How is this a war on homosexuality? How about this isn't a subject parents should need to discuss with their kids until they reach a certain age?
Why not just let the parent make the choice?
That's fine for buying books, but that's not how a typical library visit with your kid goes. Parent and child go together to the children's section, and if they stay to read, it's likely the kid will just pick up something to read themselves at some point. (obviously depends on age, but let's assume primary school age) Also, keep in mind that kids don't just read picture books, and you can't tell the contents of a book just by looking at the cover.