He was in platform engineering, ensuring the server fleet was it top-shape etc. It wasn't over him to debug OS-level bugs. Very smart guy; if something was broken and nobody else could fix it, you went to him. He'd previously tracked product bugs down to the JVM garbage collector, or RHEL. He told me about the time he tracked a bug in a binary down to the OCaml compiler— if you read the x86 spec, it turns out OCaml wasn't using one of the registers properly and the binaries, under very specific circumstances, were technically buggy.
And on Fridays he hosted an informal get-together, open to anyone in the company, where anyone could go and chat about tech. Show something off, ask about a bug, bring up something cool found on HN— everyone was encouraged to pitch in (although often we wanted to hear him do the talking lol).
People like that are amazing, and I suspect he was that smart precisely cause he knew there was always more to learn; from the machines, and from other people.