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.
The right path for AMD has always been to make their own API that runs on all of their own hardware, just as CUDA does for Nvidia, and push support for that API into all the open source ML projects (but mostly PyTorch), while attacking Nvidia's price discrimination by providing features they use to segment the market (e.g. virtualization, high VRAM) at lower price points.
Perhaps one day AMD will realize this. It seems like they're slowly moving in the right direction now, and all it took for them to wake up was Nvidia's market cap skyrocketing to 4th in the world on the back of their AI efforts...