Erin had found what appear to a map of the founder Jebadiah Springfield. She contacted Lisa Simpson to do some research on the map. She went to Hollis Hulbert who handled Springfield Historical Society.
It turned out that the map was real, there was quite a large treasure. Hollis decided that this was the time to retire. His 401K was a diaster, this made up for this.
He just needs a little time to get his affairs in order (I.E. flee from Springfield). He decided to keep the two of them in the historical society.