IBM actually owns x86 rights still. They last used it to do something similar called Lx86 which ran x86 VMs on POWER CPUs.

Developing a good x86 CPU is far beyond IBM's abilities. The rights aren't enough.

Price competitive to AMD and intel? Sure. Abilities? There is no magic, the Tellium and Power11 are each as complicated as something like Epyc and the former has both a longer and taller compatibility totem pole than x86.

Anyway this post was never about building ARM or x86 CPUs, the point is they could have done a zArch fast path for x86 for "free", so there is some other strategy at play to consider doing it with ARM.