I tend to think that coco crabs are probably rather like most predators or scavengers and are opportunists. As such I suspect they will consume on-site when safe to do so, but will try to hoard away what they feel they must to have it for themselves (and thereby need to keep from competing creatures).
I also suspect that 'need' is always with them, that a potential meal squandered = death, so basic survival probably drives all the above.
I'm no zoologist, so that's just a layman's view and set of guesses, but it seems to fit what we observe about these critters.
Would they 'gnaw' on a dry bone like a dog might, until it's gone? I have no idea - but wonder if there's a particular need to do so. Dogs seem to gain something other than nutrition from that - maybe dental health or promoting of enzymes to deal with carrion - just guesses. Do crabs have that need? Again, I 'suspect' crabs would pick a bone clean and then move on to the next 'juicy-juice' opportunity -
So, who knows, maybe Amelia remains a 'woman about town' on Niku to this day, her bones just awaiting the right thorough search so as to be found wedged into some long-gone coco crab's lair...