We recently had our main chat room frozen on the DIY site because we're not that talkative. I'd suggest a feature to allow moderators to explicitly protect chatrooms that would exclude them from these automatic freezing and deletion routines so that discussions appropriate for this forum have a place to go.
This is now implemented. Main chat rooms do not freeze automatically due to inactivity. I checked various chat rooms like Project Management, main chat room for Project Management and "Bar Sport", main chat room of Italian Language. Both the rooms are not frozen in spite of inactivity.
In PM Stack Exchange chat room, last message was posted 638 days ago before I posted a recent test message. In "Bar Sport", there are no feeds. But messages posted by feeds do not count as messages. Other chat rooms freeze even if there are feeds posting in chat room.