Submitting an essay for others to judge, and then altering it after receiving criticism is not quite doing it right. Mistakes are okay, covering them up is not however. In my opinion a better way to deal with the issue is to cover the bad joke with strikethrough formatting, followed by rationale for doing so.

I disagree. Someone found a bug in his essay and he removed it. No point repeating it to future visitors. In general, the final copy of a document does not include strikeouts.

Yeah, but it's pretty much accepted that once an article is publicly posted (much less submitted to a popular reposting site) it is final.

I find that most good blogs tend to mark such after-the-fact revisions in a manner similar to that suggested above. Otherwise, there is no coherent article for the readership to discuss. There's the version you read, which is different from the version I read, which is different from the version Alice will read tomorrow...

Yeah, but in this case, the removed part was small, not related to the rest of the article, and the most common reaction to it would be "you should remove this".

I was actually not aware that there was an accepted finality to online writing though, so that is something I should keep in mind.