Is changing a blog post after the fact unethical because someone who had linked to it on social media is fooled and looks bad?

Tim Pool makes an interesting point about “stealth edits” by newspaper stories and probably bloggers.

Someone writes a reasonably factual blog post and others link to it. Later, after the links, the blogger changes it and adds controversial political opinions. Then people who linked to the post suddenly look bad because of after-the-fact changes.

  

I often make later additions to blog posts, although usually not to change the tone of the article. But sometimes a disturbing interpretation of a fact occurs to me later and I add it.