They are literally both picking third party financial institutions to come up with evaluations independently and averaging the two. If those are far enough apart a third one is selected that both Disney and Universal agree on. How do you get from the actual setup here to "basically non-binding arbitration"?
As for what was reported, the 8.61 is being reported as the MINIMUM amount that was guaranteed based on the original agreement. Not one article or quote I have read has said that is what they will pay, just that it can't be lower than that.
I'm not even saying we won't or haven't seen spin from both, just that this current reporting of "this is what they agreed on in the original contract" isn't it.