Please take whatever I say with a pinch of salt but words such as "whiny" or "self-entitled" are far more emotive than insightful. When it comes to ideals there are people of all kinds, on both sides, from the highly intelligent and charismatic, to the... less so (like me! ^^). Also, it's difficult to label an SJW as self-entitled when you consider that most, depending on their cause, are fighting for others.
Doomsday, you can't blame Renegade Vile for not defining his point clearly when you've been just as vague, going so far as to establish that he is imagining it all from the get go without explaining why. I'm not certain if this will help since I'm iffy on the term myself but, as far as I can tell, SJW's meaning (at least within the context of this thread) refers to those who are overly aggressive in the pursuit of seemingly liberal ideals, to the point of being malicious or even hypocritical. Lustful Bride gave a nice example.