The main issue with the SJW label (as per definition of Urban Dictionary), is that it requires a lot of information on intent.
A pejorative term for an individual who repeatedly and vehemently engages in arguments on social justice on the Internet [...]
So far so good by UB standarts.
[..]often in a shallow or not well-thought-out way[...]
Judgmental, subjective observation, can be dismissed.
[..]for the purpose of raising their own personal reputation.
This is the key flaw in the definition, that makes it unusable. How do you know the motivation of the 'SJW'? Is there a separate community, where these SJW meet and brag about their achievements?
The examples that follow in the UB have issues as well.
A social justice warrior, or SJW, does not necessarily strongly believe all that they say, or even care about the groups they are fighting on behalf of.
Same problem of having to know the motivation.
They typically repeat points from whoever is the most popular blogger or commenter of the moment
So people reuse argumentation made by others. What else is new?
hoping that they will "get SJ points" and become popular in return.
I have seen this only on slashdot, where there is karma (and karma whoring). Here, JS points are almost currency. Is there any other such community?
They are very sure to adopt stances that are "correct" in their social circle.
More likely that they actually believe their cause and the social circle they live in has the same belief, or they would have left it. Also, slashdot has exactly the same way of thinking. The correct view is that tech sector and open source in particular is meritocracy, that women just don't want to be there and this issue should just be dropped.
Also interesting label is "White knighting", which also is pejorative used to mock those who defend others. On the face of it, defending the abused sounds like a good thing to do, but when you don't like it, call it white knighting, and it suddenly becomes something bad.