"Nobel-winning scientist age" is not a good proxy for "productive scientist age", for a variety of reasons. They mention specifically lag time between discovery & recognition, but you also have issues where the "name" behind the discovery is the guy in charge of the lab, but the actual discovery (and sometimes the idea) is generated by the 30-year-old postdoc / assistant prof / etc.

There is also a sampling bias issue where scientists in academia as a whole are getting older because the boomers still have a death grip on institutional positions, and academia as a whole is shrinking.