You're missing the point. It's unavoidable that if you say "you sound racist" that that attributes a trait to the person rather than their behavior, and is not much different than saying "you are a racist." The rule of thumb is address the behavior rather than the person, which is why the corrective response is supposed to be something like "wow, what you said sounded racist" It's a subtle but important difference. Then you are inviting the person to ask themself internally "did I mean what I said?" or "do I want to sound racist to other people?" instead of going on the defensive because they as a person are being labelled a cultural undesirable. If you make a statement about the person themself there's no avenue forward for discussion or correction, you just made an enemy. But if you make it about the speech, even if they get defensive about it you can clarify that you are addressing the behavior.

There are consequences here because there is username, user identities are often shared across sites, and there is a karma system here. They may be mild, but obviously karma is consequential or it wouldn't exist as a concept on the site. Your score is your aggregate reputation among other users. People fear saying things that will lower their karma.

> there's no consequence for expressing racism in a quasi-anonymous comment environment

Welllll, you never really know though.

It seems prudent to not underestimate the googling skills of future (potential) employers...

There aren't any biological tests for racism that I know of. What got the guys fired were remarks they made that 'sounded racist'. If I said to you that you 'sound German', it's likely that I'm inferring that I think you're a German. If I say to you that you 'sound racist', it's likely that I'm inferring that I think you're a racist.