Alex was an early Twitter employee, Twitter API lead at a time that many HN readers were writing Twitter apps, and wrote Programming Scala. There're a number of folks here that follow his writings with interest.
It's a totally fair gripe. One thing HN's format is piss-poor at is providing context for stories, other than the headline (and that's had its own set of issues with rewrites).
In addition to the credentials that was listed, I'd say it's relevant as its about an engineer thinking he should try founder/executive and realising that it wasn't the right fit for him now. That could be useful for the many people thinking about transitioning down the same path.
Given his affinity towards programming languages, he sounds more like a computer scientist than an engineer, frankly. I wish the two roles didn't get conflated so much.
I'm not sure a physicist is the right term, but there is a difference between your usual carpenter and someone who wants to study hammers and come up with new ways of building them and using them.
I think there's something to be said about identifying what direction you want your career to go in. In my last (pre-startup world) job I was being slowly edged into a management role- I was in charge of a team, and had meetings and agendas to assemble. I hated it- I wanted to be programming.
It sounds like Alex came to a similar conclusion. Being a CTO involves less programming than being an engineer. Sometimes it's an assumption that our career paths as engineers will take us toward being CTOs, but maybe that isn't right for everyone.
