What I've found is that it depends on so many variables between the people wanting to have the discussion that it's entirely unpredictable how it will turn out - and often unpredictable even if it's the same two parties with discussions separated by time.
I'm a white man married to a black woman. We've known each other over 35 years. We've had discussions on many aspects of the racial divide over the years, of course. I think that I understand her point of view as a black woman much better now than I did in the '80s, or '90s, or '00s, though even today she may say that I just don't get it. (And I think she understands where I'm coming from better, too.)
But the effort has been worth it. It's just very, very difficult sometimes to have such discussions.
As far as the substance of his experience with the interviewer, sadly, I completely believe it and am not even surprised. The author handled himself with dignity at every step. It had to take a lot of courage to tell it straight when the session on interviewing brought it all back up years later. So what everyone went silent? Their discomfort isn't comparable to what I suspect his was.
Telling the truth is always worth it, especially when it's hard. Hopefully sharing his negative experience helped at least one person in that session to reconsider what they probably considered to be long-settled (and probably vague) opinions about their own rightness in this regard.
tl;dr: It's easy to learn to avoid saying what you really feel and think when you're in a work environment and you know there could be repercussions. It's hard to challenge yourself and others to go beneath the surface, but the rewards are great.