I would suggest giving the poster the benefit of the doubt, as they may not be aware of the NSFW tag.
Perhaps suggest in the comments that they add the tag, then, if they dont, flag.
I have seen people do this, and usually the response is "sorry, I didn't realize, have added NSFW tag"
I have looked at the post. The author is clearly aware of the material as they've written that if anyone is unhappy they will take the post down.
I have to say it's not for me to judge, I just wondered what others think but more importantly is there any safeguards and if so who implements them?