He's the Super Hufflepuff! He's taking all the electives, which is physically impossible without a Time Turner! He was mentioned right before Harry started making thorough off-screen preparations, and then conspicuously forgotten for the rest of the chapter! Dramatic logic dictates that he's got to show up at some point, probably in some way that involves time travel.

... Unless the whole thing was a throwaway joke about how useless Cedric was in Goblet of Fire, in which case yeah, I guess it was pretty funny.