Posting a reply causes plone.protect to kick in

[pysailor]

When you post the first reply on a status-update, _idx_threadid on the statuscontainer will add a new entry to the _threadid_mapping.
The next time the dashboard with the activity stream is loaded, plone.protect kicks in (auto.py: ProtectTransform). The reason is there's a write operation: the list of _registered_objects contains exactly on item of type <BTrees.LLBTree.LLTreeSet object at 0xb5823224> - in other words, the new entry for the _threadid_mapping of the statuscontainer.