I've used them for chickens so expect they'd be ok for quail as well. They are just compressed pine sawdust so generally safe for animals. You can also use wood stove pellets they are exactly the same thing just come in bulk 50lb bags and cost way less.
Only problem I can think of is dust if they're really scratching around breaking it up when its really dry. I've mostly had it stay in pellet form unless/until it gets damp and then breaks down into sawdust. But because it's damp at this point there wasn't too much dust. I don't think it's good for any bird to inhale too much dust so maybe just something to keep an eye on.
Let me tell you a story about a man named Jed. He made this tiny ad:
Greenhouse of the Future ebook - now free for a while