My hunch is I-flybynight chose to receive email notifications and is growing tired of all the emails when their query has been answered.

Personally I am against the policy of closing threads unless there is a legitimate reason such as duplicates, abuse or way-way-way off topic in which case it is moved. Leaving a thread open allows it to be continued down the track if someone does a search and wants to check that the info is still valid or generally people have an experience that they wish to post against a topic that was mentioned in a thread.