The article says that heads and heads alone were found:

> They've uncovered large numbers of cattle, goat and wild gazelle skulls and horns in small chambers in the heads of the mustatil, but found no indication that these were kept for domestic use. Since no other animal's body parts were found, it led the team to deduce that these were sacrificial. It further suggested that the animals were sacrificed elsewhere.

Whatever it was, that doesn't sound like an abattoir.