I guess it's possible that the 3-man commission had looked at the evidence and come back with the view that it would be a 10 or even 12-point deduction based on the evidence they'd seen so far. And that to save the huge expense of a 3-month hearing, and probably an appeal, the PL were prepared to settle for less, in order to avoid the expense.
It's also possible that they were told that it was the IC's view that it was only 50/50 that they'd land the main allegations, and they wanted to try to get a result without that uncertainty, and one that satisfied the cartel as well.
It could also be possible that they did this entirely off their own bat, having discussed with the cartel what they'd consider the minimum adequate outcome.
We don't know, and we'll only know when the IC makes its findings known.