Uzi's are sub-machine guns because they fire handgun rounds. an assault rifle fires rifle rounds.
In the article those "Trained weapons experts" they're talking about are either really dumb, or the author isn't telling the truth about what they said. They call the gun a C7 when even I, a 15 year-old with no training can clearly tell that it's a much closer replica of an M16 A2 than a C7. They also say it has Auto and Semi firing modes. Correct me if I'm wrong, but isn't a C7 a semi-auto civilian assault rifle?