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.