Oh. I didn't intend it like that... as I said, I don't really find Ryo's singing to be all that interesting either. I just can't imagine trying to voice a character like Ryo.
Yeah, most young boys are voiced by women because it's difficult to get an actual little boy to provide the voice. Finding a talented enough young actor, somehow managing school as well as a time-consuming career, working around child labor laws... besides that, the kid's voice would eventually change, and then he's out of a job. It's much easier, and sometimes even more convincing, if a woman uses a boyish voice. However... playing a trap is different. First she has to capture that boyishness, since she is playing a boy. Then she has to consider that this boy would be disguising his voice to pass as a girl. And in this case, she has to sing, which is pretty hard if you're not using your normal talking voice. So... yeah.
Only dub case I can think of where they used an actual kid to voice a kid was Aaron Dismuke as Alphonse Elric. He was... 13 at the time? But most little boys these days are voiced by Luci Christian, Mona Marshall, Kari Walgren or someone like that.