I understand your point.Like it or loath it there are a lot of employees not as PC as some on here
They cannot control off the cuff remarks the employees see as banter
They will know of other cases where something has been blown out of all proportion.
Defending someone accused of prejudice or discrimination is a minefield so they stay well clear particularly in small organisations
You're describing discrimination based on racial prejudice.
If ethnic minorities didn't have any protection from discrimination at work, then do you think these employer's would be more likely to recruit them? What you're describing is someone saying a candidate is excellent, but because of their race, the employer thinks they might cause trouble, so they aren't recruited. That's exactly why race legislation needed to be brought in in the first place.
It's a lose/lose for the "excellent candidate", and win/win for the racists.