I don't disagree that the engineering can be justified. But you don't need custom hardware to achieve radiation hardening, much less hiring fucking IBM.
And to be clear, I love power chips. I remain very bullish about the architecture. But as a taxpayer reading this shit just pisses me off. Pork-fat designed to look pro-humanity.
One of the tradeoffs of radiation hardening is increased transistor size.
Cost-wise it also makes sense - it’s a specialized, certified and low-volume part.