Best I could find is here, which is an article by Randall Munroe (the xkcd artist), and states:
davean (the xkcd sysadmin) wrote the patch
This blog post links to another wayback machine page (thank you archive.org!) here, which explains the sorting algorithm and states it’s original author:
Fortunately, the math for this was worked out in 1927 by Edwin B. Wilson.