Think that might have been an oversight? Did you, perchance, try to report said insult to see what happened?
It's funny how the simple fact that a moderator can't be everywhere is interpreted to be 'coddling' a particular 'class' of user.
No, examples such as the one I cited are the rule, not the exception. Just flip through the pages in Physics and Math and you'll see what I mean. Very often a moderator is right there responding to the loonies. Their usual MO is to try to engage them in dialog and ask them why they say the things they do. It's as if they want to administer some perverse form of pro bono psychotherapy, when what is really called for is a good swift kick in the ass.
For a recent example, see the last couple of pages of Science and Pseudoscience - A Primer.