It's a specific question with a specific answer. I thought community-wiki was a ghetto for "Must-have super-awesome for $FOO" type questions.
Your question has 10 answers. Any question on SuperUser with 10 or more answers is automatically converted to Community Wiki.
This rule seems to have changed in the past six years. Here are the four most recent Super User questions to accumulate 20 answers or more:
- Easiest way to find out if user has either Windows 7 or Vista (through telephone support)?, March 2012, 21 answers
- How do I upload huge files across the Internet without using P2P?, October 2011, 20 answers
- How to find and remove “spicy” media files from my PC, September 2011, 25 answers
- What are some options for transferring large files without using the Internet?, August 2011, 24 answers (And, yes, one of the answers is xkcd: File Transfer.)
TL;DR: As recently as March 2012, it was possible for a question on Super User to accumulate 20 or more answers without being converted to Community Wiki.
(BTW, one of the above questions is by “Scott” — no relation.)
Are you sure you didn't accidentally checked the box? I don't see any edits to the question.