2.1.x: Spam module does not filter Book page content

WinXP Pro SP2
Xampp 1.5.1
Apache 2.2.0
PHP 5.1.1
APC 3.0.8
MySQL 5.0.18
Drupal 4.7.2
Spam module 2.1.1 for Drupal 4.7.x

In settings->spam I have enabled Filter book page content and Log everything.

If I create a top-level Book page or a child Book page logged in as Admin (with or without content specified as spam +200) the spam log records:

node 24 06/14/2006 - 7:12pm spam_nodeapi: skipping node "admin spam book page" for admin

If I do the same thing logged in as an Authenticated user with permissions to 1) create book pages; 2) create new books; 3) edit book pages; 4) edit own book pages; and 5) access spam, there are no entries in the spam log whatsoever for the created Book nodes as well as no spam filtering.

It seems as though the spam module is completely unaware that any Book page content even exists when created by an Authenticated user.