For what it's worth, Oracle is one of the largest contributors to the kernel, especially if you filter out the drivers subtree, which tends to skew the metrics for various reasons (lots of large generated code, almost identical arm SoC variants etc)
It would be really odd if they couldn't teach you about the kernel.
As a counter-example, Zstd is created and primarily developed by a Meta employee.
I also felt the same way upon opening the article, but companies are made of individuals, and often individuals do valuable and insightful work, even inside of bureaucratic and Kafkaesque organizations like Oracle.
