Here is where you are going to run into problems. NSFW can't be the first tag because it is filtered by the site. So really your attempting to bypass the site's preferences (for lack of a better word) by posting it anyway with it afterwards.
It's open source so I am sure steemit.porn will come around and have additional freedoms there, but as for steemit.com it is it's own site and some things have been decided they do not want on the site. Anyone bypassing this probably won't have an easy time.
I say bypassing as you acknowledge using NSFW first hides the post, and yet still want to post content anyway.
Oh and in your list of proper flagging guidelines is abuse of power, so it is entirely proper that it was done by that statement. Seriously though, it's hard to make the argument "I can post whatever I want, you can only downvote based on these rules though"
@clevecross there is a couple flaws with your logic.
That statement assumes that Flagging is the same as Downvoting and that is not the case, there is no DOWNVOTE feature on Steemit but if there were a Downvote doesn't destroy a persons reputation score, it only reflects on the actual content being downvoted. Where as flagging a post/comment affects the reputation and the content being flagged.
Downvote doesn't exist and I meant flagging, the words are the same to me. Again I stand by my statement because the reputation is also this site only.... steemit.porn or any other portal to the blockchain wouldn't have the reputation factor into it. My point was just it's a soft rule to the site that has been implemented, and there is intent to bypass that. I understand being flagged is harsh, my statement though was just it's hard to say I am free to post content I want to post, you can only flag under these circumstances.