If your goal is to stop the spread of the data, perhaps... but if you are caught with one of these guns now, you might also be prosecuted under arms control/export laws.
Also they're not saying the data is illegal, it just may be illegal to "export".
ATF agent: Oh, you got that from a torrent? Did you also seed the file?
You can see where this is going, and it doesn't have a happy ending.
If you do make one of these though, for the love of God embed a chunk of metal. These things wouldn't be legal without it (metal detectors).
Why you have to explain anything? As far as I know, you do not owe anybody to prove that you possess anything you have legally, if they suspect it is illegal they have to prove it.