As to how they can justify using Mind Melding as a metaphor for alternative sexual behavior, and claiming that in the era in which the show is based that it is perceived as abhorant? I have no trouble believing that we happen to be peering into that universe as the last vestiges of bigotry are being stomped out. It certainly helps to explain how humans can be so prominent in the Federation eventually. Since it is unlikely that by the time of TOS we'd have advanced beyond our betters in technology, we have only our diplomacy and human nature to set us apart and perhaps allow us to take a lead role in the Feds.