You're correct. There is no education discount on refurbs. But they were just stating that the cost of a brand new one with the educational discount applied was more expensive than the cost of the refurb.
FYI, if you use Discover credit card, you do get 5% back if you go through Shop Discover. It does say it does not include iMacs, but I did it anyways and got the $86 credit on the base refurb 27".