I've never heard of "Chesterton's Fence" before and appreciate the introduction to the term. That said, I don't think your application is correct. The OP in this case is not the agent of change — he did not "reform" anything and does not have the capacity to act, he just analyzed/synthesized existing data.
(Also, on reflection, "Chesterton's Fence" is an unnecessarily complicated and overly verbose way of saying: "The MTA probably has a reason for the change.")
