Taking a couple of guesses here, but your question has just been awarded the Famous Question Badge. I would imagine that Jamal saw that badge go through, and then looked at the question, and figured it needed to be a better example of site policies.
In general, I would not advocate retroactively and 'blindly' applying policy changes to 'older' questions. In this case, given that your question is very highly viewed, it should be a good example of what we want Code Review questions to look like.
The reason that we don't like changes to the question is because it adds confusion to the answers... should new answers critique your 'conclusion' code, or the pre-answer code.
My preference is for high-profile questions to be good examples of best-practice for the site. You asked for a reason for the edit, and you also suggested that your preference would be to leave the text alone....
As has been suggested in a comment, the logic behind the policy is laid out here: For an iterative review, is it okay to edit my own question to include revised code?
Leave the question alone
A self-answer would be a good option at this point (even this late in the day). If you don't want to do that, I would be happy to roll-back the edit, and add a note to the question with a "Please note, this practice of self-answering as an edit to the question is no longer allowed on Code Review, please see ..."
Your call, preferences?