Craig Baird's take on this incident is interesting to say the least. He says there were too many cars that had small breaches... so the answer was not to penalise the car/team that caused all of the other cars to have small breaches? Interesting, but ******** in my opinion.
Craig Baird said ''One car moved slightly forward which didn't allow one of the Penrite cars to come in''. I would've thought that constituted an unsafe release and was the trigger for the whole incident
. Without that happening the zipper effect could've taken place and no-one else would've been
forced to breach any rules. Team 18 were just too eager to not impede their second car that they impeded everyone else, that's all.
They have come up with some sort of solution to double stacking though. Two laps of 80kph speed limited caution laps so one car can pit the first time round and the second car on the second time round. It works but time certain finishes could possibly occur more often with the extra lap at 80kph... and they're yet to figure out what will happen at Bathurst because of the length of the lap.
Source:
https://www.v8sleuth.com.au/podcast-race-control-supercars-dsa-explains-the-calls/ (at about 12:35 in)