The idea is interstate transport is forbidden- has nothing to do with the reason why you are sending ivory across state lines. If they open up a package- see a cue with white inlays- you can bet it will be confiscated - I will not risk it anymore with the USPS.
I agree the odds are probably low- but I would suspect the odds are lower sending it outside the USPS - especially outside the USPS system via OVERNIGHT - just a higher cost now that we need to accept to be safer -so how many folks want to risk losing a $ muti thousand dollar cue to the USPS- I am not risking it.If you are shipping a cue within the USA to another address within the USA, then what are the odds of the package you shipped being inspected for some sort of illegal material? I think highly unlikely to get inspected, and confiscated.