Another problem is that there appears to be no activity-log entry for a topic that becomes locked or moderated automatically due to group time-out. The log shows "xyx unlocked topic," and then the topic appears locked again the next day with no explanatory log entry. So at the bare minimum this is a logging - er - failure (not a bug! not a bug!;). It makes the re-locking *appear* to be a bug to moderators trying to figure out why the topic shows up locked the next day after they locked it. Having a log entry for this would at least mitigate confusion.
So to summarize, these are my suggestions, and then I'll beg out of this thread:
Best solution: provide a "Do not relock [remoderate] automatically" setting that can be applied selectively by hand to individual topics in a group with a auto-lock [auto-moderate] setting
Temporary mitigation of confusion: either disallow the unlocking [unmoderating] of automatically timed-out topics, or provide a warning/confirmation box
Long-term logging improvement: add log entries "topic automatically locked [moderated] due to group setting"
Messages are the sole opinion of the author, especially the fishy ones.