To be clear, option 2 didn't mean the loss of banked 75/05 pensions, just that all personnel would be moved from 2015 into the '15 scheme. I guess those who stayed on '75 would get the hit.
The strong implication was that option 2 was likely as it removed the reasons for the challenge in the first place, which was illegality down to age.
Edit: They did say they recognised that some gained by going to '15. So it wasn't straightforward, but the decision is up to the treasury.