Although there's no cam on it, a locking lug is of course present on barrels of FiveSeveN and Ruger-57. The cam surface is on the lever in the slide.
Anyone who faults you for the faithful transmission of Ruger's corporate communication ought to apologize. That said, it's far from the first time the manufacturer posts something incorrect or misleading in regards to the operation of their firearm. Look no further than LWRC's SMG-45, which they describe as "short-recoil delayed blowback". No lesser authority than Ian MacCollum described Benelli B76 as intertial locking system -- according to the wording of the actual patent, no less -- when in reality it is a delayed blowback.
People discussing the FN and Ruger ought to ask themselves: what does the lever with cam surfaces actually does in the frame of the pistol? Why is it included in the design?