I learned after posting this question that our help page is incorrect.
It currently states the following:
The spam and abusive flags are designed to automatically eliminate truly disruptive posts through the collaboration of the community.
- 3 flags -- post is banished from the front page.
- 6 flags -- post is locked, deleted, and the owner loses 100 reputation.
However, it was confirmed that, in reality, it only takes 3 such flags to delete a post on our site.
Our help page should be updated to reflect the actual situation here. (I'm assuming that we go straight to deletion without front-page banishment at first.)