A lot depends on how interested the child is in the topic, and how she responds to difficult topics. I wish I could find the reference at the moment, but I read an article a while ago about how children will persevere through very difficult material if it is personally interesting to them. For example, how Homer Hickham learned rocket science in October Sky.
I've seen the effect with my own son, who is seven but reading at a 5th grade level, largely because getting better at reading gave him access to more interesting superhero books.
I have seen research that shows the opposite effect you are concerned about, where it diminishes interest in a subject, but those are all when an advanced topic is forced on a child before she's ready, like kids thinking they're bad at math because for a while they were six months behind their classmates developmentally.
If the pressure isn't there, you might be surprised how much kids soak up. I've had my kids ask to watch with me when I'm watching a graduate-level lecture. It's interesting to me, so it's interesting to them, even if they don't understand it.
Factoid books are especially flexible, because kids can digest as much as they are able to handle, and revisit it later. They don't have to understand the entire book in order to understand part of it.
I would say go for it. The worst that would happen is you're out $15 for a book that's going to sit on a shelf for a few years.