How can text be NSFW? No one except you would know the actual context and longer story but you, so unless there are words like "PENIS INTO VAGINA" with big letters, I don't see how any plaintext can be NSFW.
But in reality it's just a common short-hand content warning, similar to [PDF] right before a URL that ends in .pdf.
> When AM had altered Benny, during the machine's utterly irrational, hysterical phase, it was not merely Benny's face the computer had made like a giant ape's. He was big in the privates; she loved that! She serviced us, as a matter of course, but she loved it from him. Oh Ellen, pedestal Ellen, pristine-pure Ellen; oh Ellen the clean! Scum filth.
But I'm sure you know all of that. The warning is not for you personally, you may disregard it.