I honestly don't see how they could have an ATAR cutoff but then pick and choose between which applicants with that ATAR actually get an offer.
I think they would need to incorporate a method to deal with this scenario. For example say 16 spots out of 20 have been offered to 99.65+, then there are 20 applicants on 99.60 vying for the remaining 4 spots. Do you think they would (a) make only 16 offers or (b) over-offer 36 spots or (c) have a way to differentiate the 20x 99.60s?