Stelfox is right.
words within a given context - i.e. a discussion board - are not empty and do not exist in a vacuum. They have effects on other people and on the shape of the scene they are expressed in.
I didn't read this thread until recently, and I can't say I'm sorry, because it is upsetting and nauseating to come across language like that. And if people feel they can say shit like that without repercussion then the tone of the board changes and certain people (people who are anti-racist and people who are targets of that language) will not come here. Other people (people who like to say that shit) will come here. and what a lovely place this will be THEN.
This is even more true if it is unchallenged.
Racism isn't some nefarious plot by mustache-twirling villains who are evil to the bone, it is a sett of attitudes justifying racial hierarchy, that are embedded in society, and that is reinforced by repeating it. That crap needs to be challenged and shut down --even MORE so if it is unconscious on the part of the speaker.
If a person didn't think about the meaning of what they said, or "didn't really mean it" then they haven't made a conscious choice to support it. Having other people challenge them on it forces them to consider how much they want to stand by their words. What is gained by making dissensus a "safe space" for racism?