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.
These were precisely the arguments for 'x86 will entrench Intel for all time', and we've seen AMD succeed at that game just fine.
... after a couple decades of legal proceedings and a looming FTC monopoly case convinced Intel to throw in the towel, cross-license, and compete more fairly with AMD.
https://jolt.law.harvard.edu/digest/intel-and-amd-settlement
AMD didn't just magically do it on its own.