Even a retrodiction can be impressive and/or interesting if it is a sufficiently "nothing up my sleeve" [1] type of prediction. I don't know enough about this field and the article isn't informative enough for me to guess, but it's possible that they made a retrodiction where they didn't tune the parameters for it explicitly and got near the correct result directly. In that case, it would at least constitute some sort of clue, even if it isn't necessarily correct. Or they could have tuned the heck out of it and glossed over it in the article, I dunno.
reply[1]: https://en.wikipedia.org/wiki/Nothing-up-my-sleeve_number