While it says that "[...] you need to use a Chromium or Webkit browser to enjoy MONOSPACE live." (emphasis mine), it does not say "DO NOT USE FIREFOX UNDER ANY CIRCUMSTANCES, it will mess up your device for minutes" anywhere.
We saw so many (warranted or unwarranted) "Best viewed with Chrome"-statements on the web already that we became desensitized to it years ago.
No, please don't add derision to HN threads. When someone else is wrong, it's enough to supply correct information. That enhances the thread without damaging the commons.
I think some selective derision is warranted.