I only see this.
In both SP and MP, KILLZONE SHADOW FALL outputs a full, unscaled 1080p image at up to 60 FPS. Native is often used to indicate images that are not scaled; it is native by that definition.
and this.
In Multiplayer mode, however, we use a technique called “temporal reprojection,” which combines pixels and motion vectors from multiple lower-resolution frames to reconstruct a full 1080p image. If native means that every part of the pipeline is 1080p then this technique is not native.
Where does it say both SP and MP are upscaled?