That's it. IMHO, referring to the thread as "hidden racism" is unfair. I do think that mentioning race in regard to actual experiences brings it close, but I don't think it was in any way intended as a racist comment.
I think it's really important that we all speak up against racism, sexism, or any other kind of negative -ism, but I think we have to be careful not to see something which was never intended. Sometimes (and this is only my opinion) it is all in the eye of the beholder.