At a guess that's because my comment attracted more up-votes than the other top-level comments in the thread.
I generally try to include something in a comment that's not information already under discussion - in this case that was the link and quote from the original README.
the code is not public, so we can't know. i think it's much more nuanced and certain users' comments might get a preferential treatment, based on factors other than the upvote count - which itself is hidden from us.
