I'm not saying their original statement wasn't what they meant when they said it. My only point is that hard coding things is a common development shortcut. Everyone knows that it's bad practice, but when you're developing software for basically your own use it doesn't really matter.
Not only that, but Lemmy is open source. So anyone that is so inclined could remove the filter on their own instance if they really wanted to.
My opinion might change if I saw the list of banned words and it contained things other than common curse words and slurs, or only included slurs for one group. But without that, this just seems like a development decision in spite of the poor reasoning behind why they implemented it in the first place.