Is somebody claiming that some of the cometary material is less than 1Ka (kilo-annum) old? I doubt that any of that material is younger than 3Ga
, and probably older than 5Ga. Perhaps they mean that the material was mostly dislodged from the comet over 1000 years ago. Fine, but that's not the age of the material, which is generally taken to mean the age at which the material came to be in its present state (vs. location).