Since this evidence came as neaderthals were disappearing from the scene, and knowing that homo sapiens already practiced canibalism—its not a big stretch to figure that
these neanderthals were eaten by humans.
The reason would be pretty simple. The homosapiens would do it for the same reason that humans have more frequently practiced cannibalism from the beginning of time—not for survival — but rather to gain energy/power/mana/juju of the being they had just fought to the death with.
Since the Neanderthals would be such a deadly opponent—its not a big stretch to figure that they were hunted ritually to gain their power.
Chimpanzees are known to raid rival tribes and eat the victims - it's a prize but they won't eat their own (I assume).
If the consumed are victims of raids then I kind of wonder if that is one of the origins of burials (evidence the Neanderthal's practiced it). If you bury your dead they can't be eaten by animals or rivals?
Also explains the small % of Neanderthal DNA. It was probably from war boot slaves from homo sapiens sapiens raiding Neanderthals?
/bingo