I think it's needlessly mocking, but it is not a label: it has an actual definition, and I'd consider anyone who used the word outside that definition to be using it incorrectly. It refers to a specific set of behaviors. Bigot and racist used to not be labels, until people started applying the terms to everything.
You're trying to be pedantic and failing. "labels like bigot, racist, etc." have actual definitions, too. Your use of the term "sjw" is just hypocritical. It has no more of a clear definition than "racist". It just happens to suit your narrative.
Well, fair enough, you're right that SJW can be used as a label too.
My original flagged comment was actually "The invigorating fervor of social justice"; I didn't use the term "SJW." It was a sassy thing I wrote because I thought it was funny how the obvious comment that took no courage to write was shooting to the top as usual. I was making fun of people with who post passionate, rallying cries in the spirit of "we must stand our ground," knowing full well they're on a message board that will congratulate them for it, and, while they're at it, being rather boring.
As for my SJW comment, I was explaining to tomlock why people use "social justice" negatively. I should've added "e.g." before "social justice warrior."