FWIW, I was always under the impression that the AFPS paid preserved pensions at 60, when I expect mine. No goalposts moved in that regard for me. I agree that your RAO may have misled you.
I do however have a beef about the AFPS. When I was considering leaving, I asked for a pension transfer value, as I was considering taking the value of my AFPS with me. I called the AFPS enquiry office, to be told that the office is not staffed to deal with enquiries!!!!!!!
I had to go to the Occupational Pensions Advisory Service to force them to give me a transfer value. Quite outrageous that I had to do that to my employer, and indeed was a nail in the coffin of my service career.
I dont think you have been "done over" in terms of the rules, more in terms of disinformation.