I had the same problem, but i found him

My problem was that id done "skeletons in the closet" i think? where Carl the Farmer has murdered someone, and because i got the exp for it i assumed all was said and done.
But i had an itching thought to try the watch tower Quincy was on, and Carl's Farm just because id looked everywhere else.. and there was Rodney, arresting Carl.
It seems though that you had to approach to trigger the scene, so no matter how long you leave it, Rodney wont be at his desk until youve done this.
Hope this helps, and prevents any others frustrating over it