Well by that logic it was stolen by the person who dug it up in Italy. After all, there’s someone walking around Italy today that is the heir to this sculpture. You have to draw the line somewhere.
At its zenith, the Roman Empire included these today's countries and territories: most of Europe (England, Wales, Portugal, Spain, France, Italy, Austria, Switzerland, Luxembourg, Belgium, Gibraltar, Romania, Moldova, Ukraine), coastal northern Africa (Libya, Tunisia, Algeria, Morocco, Egypt), the Balkans (Albania, Greece, Hungary, Bosnia, Slovenia, Croatia, Bulgaria, Turkey), the Mediterranean Sea, the Black Sea, Asia Minor, and some parts of Mesopotamia and the Middle East (Syria, Lebanon, Iraq, Jordan, Israel).