Disagree. You’re assuming that the quality of hires is limitless. In practice it doesn’t work like that. Unless you have a good reason to want the next Einstein or even Jeff Dean, you can hire a more that good enough person with limited time and resources and even a diverse and good enough person if you throw in some extra time and/or resources.
The assumption is that more competent hires do a better job on average. Aerospace is not an easy field, but even in much more simple jobs competence matters.
Yes, more competent hires do a better job. But there is a limit to how much competence you can hire per person. That means there is a limit - or at least severe diminishing returns - to how much more competence money will buy you.
That means you can opt to spend that money on DEI without losing out on competence
What limit? If you optimize for DEI your hires will be less competent on average. Possibly substantially less competent. The difference can mean the difference between life and death.