The difference is that a different natural skin pigment is prominent and immediately obvious, so those unaccustomed to it are prone to comment on it as exotic. Absent flirtation and/or PDAs (which would have been a MUCH better way to handle that if Jordan/Sanderson insisted on token gay dudes) homosexuality is not, and it is not something totally foreign to any one cultural experience. Like lill said, with Aes Sedai pillowfriends it made a lot of narrative sense. Jordan/Sanderson might have done something similar with Borderland or other soldiers on extended campaigns, maybe something like the Theban Sacred Band.

Instead, the sexuality of two minor characters in AMoL is thrown in apropos of nothing, just "here, have a gay guy." That is a true non sequitur because it totally lacks precedent in any of the series' other books, and has little bearing (in the first case, none) on the narrative. Gratuitous non sequitur; it is a waste of ink.