Why it is becoming an issue is because there are a couple of new diseases floating about that we do not want, sudden oak death, pine pitch canker and guava rust. As the research is new as to what species can host the diseases the things that they confiscate change over time. The antler would have been confiscated under ordinary circumstances anyway as it can host a range of diseases including anthrax or rabies. I am surprised that camel bone made it through but then again I have seend some interesting things make it through that should never have