I suspect it's mostly guys as well, not because there aren't homopohobic women around - there are plenty - but they tend not to comment on these articles so much. (The reviews themselves, btw, are all signed by male reviewers, who sound puzzled and "I never saw that coming", but not hostile.)

The phenomenon itself is well known to me (wasn't there also a section of the Game of Thrones tv series fandom shocked when Remly/Loras got screentime in s2, in pointed contrast to the reaction to the scenes in Littlefinger's bordello?), but it was never so glaringly hypocritical as in this case, because Black Sails really featured (explicit) female same sex pairings from the pilot onwards. You literally can't watch this show without encountering some interaction (verbal or physical) between people of the same gender who share(d) a bed (and other places) in every single episode. So to object the first time it's two men really can have only one reason.

(This morning when I looked the wailing fanboys have only gotten more vile over night. A new tactic is to say they'd be fine with sex but hate "relationship drama" on their pirate show, therefore, giving the main pirate a meaningful romantic relationship with another man is wrong and they'd object just as much if it were a woman. Strangely, the show never has been without "relationship drama", either. Flint's main rival for Most Feared Pirate top spot has been obsessively in love with the local female kingpin (who has very mixed feelings about him) from the pilot onwards, their up and down relationship got considerable screentime, and again, those same fanboys didn't object. And then there are the women involved in the on screen same sex pairings, who, gasp, do other stuff than having sex with each other, with the sex being part of their, well, relationship drama. In conclusion, the "This ruins the show for me!!!" crowd really could not be more obvious as to their motivation.