If it was possible to write an effective slur filter, I would not find it completely objectionable. Not because that would be useful to stop people saying completely shit-headed things if they really wanted to (I strongly suspect you could get the entirety of Mein Kampf past that filter), but as a "people who use these words are not welcome" signal, which definitely has some value.

As it is, it's bashing the problem with regular expressions, and doing so badly. I mean, some of those words actually have completely different, non-offensive meanings in certain communities & contexts. (One of a few I spotted: Last time I used "retard" was in the context of ignition timing...)

Writing an effective slur filter is undesirable. No one can stop people saying completely shit headed things. For one, people just work around it. And more importantly for every shit headed thing you restrict you also cut out someone else, even if it's just because of their perception of constraints. The mind has a funny way of editing thought before it even arrives. We can't afford this anymore in our online spaces.

There's also a language problem: "retard" is a common word in french which bears no insult in it and simply mean "late" like in "being late to work".