“Where was the export license for this unit from the US to Italy? “
You hit on an excellent point: Nuclear technology requires an export license as it is an ITAR regulated item. I am an ITAR trained and certified professional. :)
This never occurs to a con artist
If the technology was originally developed in Italy, then he's not "exporting" technology, only hardware which he could just as easily construct there.
For the US government to convict him, though, they would need to prove beyond a reasonable doubt to a jury in open court that a nuclear reaction was occurring, now wouldn't they?