I think it is confusing. I could hardly see the picture in the link but I went to Ravelry and had a closer look.
It does sound like it says that you continue as established, and all the preceding rows have ribbing, but it is clear from the pictures I saw on Rav, that you don't continue to knit ribbing. It's reverse stockinette everywhere but the cables. So, after you do row five, switch to reverse stockinette except for doing the cables. That should work.
By the way, several people on Ravelry commented that the instructions for this sweater were not (how can I put this nicely?) well written.