Wade/Unique said that she had a hard time at school and with her family. (I'm going to go with female pronouns, because that seemed the clearest the audience was given.) Coming out to the general public like that really would be very dangerous. Kurt was regularly bullied and harassed, and Blaine was gay-bashed. Kurt would be very well aware of what could happen. At least Kurt had the support of his dad and of some of the members of New Directions, and eventually all of the ND members. Blaine doesn't have support from his family, but he found a refuge in Dalton, and then gradually with New Directions.
Deconstructing Glee liked the show. If I'm getting it right, DG said that just because Unique said to Kurt that Kurt identifies as a man, that wasn't the final pronouncement. But DG thought that Kurt was almost completely sure he was a man. I believe the theory that Kurt was forced to think about it, considering how much he was called "Lady" and so on. Kurt did say to Burt, "I'm a guy." He's a guy who queers gender very frequently and sometimes deliberately.
RM (Racheline Maltese) of Letters from Titan thought it was a sneaky show about authenticity (http://lettersfromtitan.com/2012/04/18/glee-authenticity-play-and-adulthood/). Kurt usually seems so very sure of who he is, how he's presenting himself, and how others perceive him. He and Blaine are both very conscious of performing gender. Though they come to it in different ways, they meet in the middle. This happens with a lot of their relationship.
Unique was right, though. If anyone should have understood about gender performance, it was Kurt. Kurt understands about playing with gender, and at first Unique said it was a game. It turned out to not be a game.