Yeah the white clumpy stuff is not bone....it is urates, which is a hard form of urine. Almost all reptiles leave urates and not all of them eat mammals.

As for the impaction business. I have never heard of a ball python becoming impacted from ingesting acceptable substrates (wood shavings). Their digestive systems are very strong.

That being said, the big indicator of impaction is a hard bottom. If the area around the vent is still squishy and malleable then you are good to go.