You just need to have at least two different users talking in a room and to not leave a room empty (empty based on messages, not users logged in) for two weeks in order to keep it alive.
It is a minimal requirement really, so just pop in every now and then (but within 14 days) and it should stay open.
A possible alternative which would keep the room from freezing and also it would be clear which messages are "fake" - even without having to go and check the content of the message - could be using a bot for this purpose.
Generic bot would post a message after a few days of silence - this would prevent the room from freezing. The message would put the room ...
It is ludicrous that Google-Fu is subject to being frozen. There is advice all over the place for some matters to "take it to chat" and yet 93,441 users here may not be able to.
At the very least the Help Center might caution "but don't bother to try to if there has been no eligible activity there for two weeks".