Hopefully your management is trying to answer the following question: is said middle-career dev outproducing their past self, and others who still look at code, with:

1) submitted changes that don't need any more revision than their previous human-written ones when it comes to code review?

2) no increase in bug incidents

3) no slow-down in peer work or future work caused by humans-or-agents having to fight increasingly overly-complicated, poorly-factored, copypasta-style code or god methods? (this might not be evident yet)

(Another question is how well is this person doing their job as a reviewer, making sure to keep the product quality bar high, without looking at code?)

Anyone in an org with coworkers no longer writing code needs to be making sure their managers have a pulse on the long-term health of the product to see who's doing it well (lots of test coverage, shipping only super-high-quality, refined-from-multiple angles stuff) or just being lazy (shipping first drafts that continually add debt to various files and methods).