If the items in the backlog aren't related to the OKRs, then it's possible that they should be thrown our with the new cycle like the author says, but I wonder if it could mean that the OKRs need to be changed in certain situations as well. If there are things the teams value in the backlog that aren't part of any OKRs, and the dev teams are in some sense closer to the product than upper management, then that input should be filtered back up to be considered by upper management since the teams "on the ground" might be seeing information that the management doesn't have.