I wholeheartedly disagreed until I saw your point (I think). The post still has your name beside it and you disagree with someone changing your words. While I don't find it a big deal with this, I kinda agree in spirit. Maybe the poster name should be changed too. However, folks would then be upset about not getting their sweet, sweet karma.
Also the fact that he can fundamentally change what a user posts and then choose whether or not to disclose it in comment section is a flaw.