Ahah this! When reading the post title I was wondering if Twitter backend end (or even front end) source code had leaked. As a candidate I would give minus 1 point to the interviewer ;)

It screams "non-technical manager" (or journalist, or politician, et c) to me (though that doesn't seem to actually be the case, here?)

I don’t, for one. From the title I thought this was about the code that runs the Twitter back end. I would call this “markup” or “HTML”.