taxonomy_access update causes forum topic to be unlinked from forum

MySQL 4.0.24, php5, apache2, drupal 4.6.6, taxonomy_access 4.6.0

If users don't have update privileges to a forum, they will still be able to update their own topics (which is good, IMO), but when the update is complete, the post will disappear. It is still linked in the Forum blocks, and can be accessed with a node URL, but it is unlinked from the forum. If you give users update privileges to the forum, the problem disappears, but then they are able to edit other users' posts. Examining the mysql log reveals the following

Without update privileges:

DELETE FROM term_node WHERE nid = 834

With update privileges:

DELETE FROM term_node WHERE nid = 834
INSERT INTO term_node (nid, tid) VALUES (834, 4)

Similarly, executing an INSERT INTO makes the topic reappear.