So, GIVEN THAT THIS CASE IS MORE LIKELY, what are LOGICAL scenario's in which Sanji's face could inspire "only alive" status.
Your opinion seems to be #1, #3 are the likely possibilities that I have mentioned. Why is #1 more likely than #3? #3 is random. It is a boring plot device, and doesn't add that much depth to the story. Wow, some world noble we don't know of has the hots for Sanji, "yay"? What's she gunna do, send more marines to attack the strawhats? lol the marines already are trying as hard as they can. Could this set up Sanji as a slave arc?? Do you really think Sanji is going to be captured at any point? Judging by what's happened in the story so far, where they need to go, sanji's fighting prowess, Luffy's faith that his crew will get their jobs done this is not likely. Oda would have to break several one piece themes for Sanji to get captured, and thus for this random world noble to get their hands on Sanji. i.e this would be pointless, a waste of a panel for a joke that isn't even funny and would be hard to execute.
You seem to have made a whole story around what will happen next in my suggestion and why it will be bad.
I am not suggesting that Sanji will get captured because someone in the Government like him.(That would be more likely if say, he was related to someone in the government)
And I don't think it will be woman. More like an Okama.
As for not adding depth to the story, that's true. But everything doesn't need to add depth to the story.
The last poster surely didn't. Neither did any of Chopper's posters. And Franky getting pissed at Usopp's gag bounty is not adding any depth either.
I find the event likely because that's how Oda usually treats Sanji.
The idea is to try to predict the future using the given premises and details present in the story. This is never 100%, but anything that is "more likely than not" is generally reasonable to assume true, unless future details contradict that particular assumption. For instance, perhaps that picture isn't Sanji's "real" face. Maybe when he is in love his face actually physically changes to look like someone else(again). Perhaps this is Oda making another joke. But given that Sanji often makes that face i'm going to assume that face constitutes his "real face".
In this case we can safely enumerate reason's why Sanji's face COULD be important the world government. You can't say Sanji's revealed face is important to the world government because Sanji's curley eyebrows annoy the world government officials. This makes no sense. There are limits as to why or how Sanji's revealed face could effect his bounty poster. Of these possible reasons, some are more likely than others.
You don't seem to be much of a theory type, if you can't deductively reason.
As I said before, even if the face reveal is important, how does that lead to him being a noble/royal?
Why would a noble make special "only alive" status and at the same time only give a bounty of 177mil? It is too low for anyone with enough influence to change bounty posters.
He is important enough to make a special poster but not enough to pay half of what they would pay for a mermaid? Seems ridiculous to me.
But if you still don't get it, that's fine. We will just have to watch how this all plays out.