My only guess is they have a parallel skunkworks working on the same thing, but in a way that they can keep it closed-source - that this was a hedge they think they no longer need, and they are missing the forest for the trees on the benefits of cross-pollination and open source ethos to their business.
As a total outsider it seems to me that maybe one of AMD's big problems is they just aren't set up to take advantage of the global talent pool in the same way Nvidia is.