By definition this weapon is not an "assault rifle" ergo it does not qualify as the world's first, however it does qualify as an "assault weapon". Because the weapon is not capable of selective-fire it disqualifies it as being labeled as an assault rifle. There are 5 characteristics which must be met to qualify as an assault rifle:
- Is a carbine sized individual weapon with provision to be fired from a shouldered position.
- Is capable of selective fire.
- Fires from a locked breach.
- Utilizes an intermediate powered-cartridge.
- Ammunition is supplied from a large capacity detachable box magazine.
To be classified as an "assault weapon" however the weapon must meet only 2 of 10 set criteria.
- A detachable magazine holding more than 10 rounds.
- Military-style appearance, including semi-automatic replicas of military selective-fire assault rifles and machine guns
- A folding or telescoping stock
- Attached grenade launchers such as the M203 or rifle grenade
- On rifles and shotguns, pistol grips that extend vertically from the stock
- A bayonet lug
- Threaded barrel capable of accepting a flash suppressor, muzzle brake, or sound suppressor
- Weapons that include a barrel shroud
- On pistols, those on which the magazine attaches outside of the pistol grip
- A forward mounted pistol grip
And our weapon in question here meets 2 if not more of these criteria. So in review, it's not quite an assault rifle, but technically is classified as an "assault weapon".
Edit: Upon further investigation on Wikipedia it says that the weapon DID indeed have a select-fire switch, however I can't find it in any of the pictures I've found of the rifle. So now that just leaves the debate on whether the 6.5mm round is an intermediate round to qualify it as an assault rifle.