In https://news.ycombinator.com/item?id=45831614 jack1243star pointed out the possibility that English might not be Kiki's first language and they perhaps even have used ChatGPT to make the comment sound more polite.
Making a comment sound more polite should be done by addressing the other person correctly and respectfully, and making sure that you are actually responding to the issues that have been raised. When whatever you wrote is so completely offensive and disrespectful, asking ChatGPT to make it sound more polite will undoubtedly make it worse. Like writing "Sorry, not sorry", when the content of your message clearly conveys that you're "Not sorry". It only adds to the disdain of your original message, putting even more emphasis on the fact that you are wasting the recipients time and patience while refusing to show any remorse.
“Sorry for your feelings” comes off as dismissive and avoiding taking ownership for the lost work and years of volunteer contributions.