The conclusion they are drawing from this data is extremely problematic. The actual survey they did (http://publicreligion.org/site/wp-content/uploads/2014/08/AV...) asks people to list up to seven "people with whom you
discussed matters important to you". 63% listed four or less people. From that they are extrapolating to the person's entire social network. For all of the four closest relationships, a majority of people listed someone that they are related to. Obviously, that isn't a representative sample of the races in the person's social network, because a person's relatives will usually be the same race as them.
I think software dev has interesting cliques. I would imagine most government/security work is white and a rare black due to American citizenship ( this may change over the next two generations depending on various political relationships.).
I have the exact the opposite experience in tech. I can count the whites with my fingers. Granted, blacks appear to be rare as well, but there are plenty of Asian and Indian.
What would be very interesting is to see how this changes over the next few generations. I optimistic, in a south park kind of way, that race will not be an issue in four generations. I guess one could say that would be a pessimistic viewpoint.... I mean it sure is depressing that we can't unify for... I don't space or something more interesting...