Right, but that was sparse and unlikely to be detected, and the author is talking about the portions of the sphere which travel at near speed of light catching

Right, but that was sparse and unlikely to be detected, and the author is talking about the portions of the sphere which travel at near speed of light catching up to earth. If human progress is measured on the scale of reaching near-speed-of-light travel, it is easy to imagine being thousands if not millions of years off.