How are they a boogieman if they're legit a thing and get popular on the internet because of the way the big tech companies promote extremism? It's like saying /pol/ is a boogieman. Obviously right wing extremism exists too.
Making a character gay for the sake of brownie points is the SJW thing in a nutshell. It's thoughtless, uninformed left-wing politics. It was dumb, it wasn't written well, and they were probably hoping it would get them talked about since the show itself wasn't exactly lighting the world on fire. SJW bullshit was a hot topic when the episode aired.
The way I see it, a SJW is anyone who's a racist douchebag pretending to know a lot about other people while actively being condescending and misanthropic. They say things like, "the blacks can't do this, and the gays can't do that", like skin color or sexual orientation were some sort of monolithic experience. They'd say, "Oh, the gays aren't on TV", so some people in the industry added "the gays" to their work.
Do Korra and Asami really come across as people who are homosexual? Or did they just spontaneously become "the gays" at the last fucking minute. Because I felt like it was the latter.