Just want to mention that some believe bone dust is TOXIC, so be careful if you need to do a lot of sanding to shape it to size.
I agree that the saddle should never be glued into the bridge but I disagree with not having a bit of glue on the nut. There is a safe way to remove a nut from a guitar, and just enough glue keeps it from slipping. AO
None of the higher end classicals I've ever owned had the nut glued in place. It's no problem to quickly and easily get the nut in perfect placement when changing all the strings at once. If changing strings one or two at a time, the ones left in place will hold it. That having been said, I don't see any issue with putting a tiny dot of glue on it to hold it in place as long as it can be easily removed by lightly tapping it from the side, and it doesn't necessitate taking a chisel to it. Once the nut height has been set, it probably won't need to be changed, so lightly gluing the nut shouldn't be a big issue. The bridge saddle should never, ever be glued.
The idea of taking a chisel or screwdriver to a $5,000.00+ guitar gives me the willies.