I don't see a question there.
Technically, the Antagonist's function is reconsider/avoid. His function is to make the Protagonist's life hard. You're right, in another story he could be on his merry way Obtaining... but not this story. In this story, he is reconsider/avoid.
I agree with @mlucas that starting with an OS sequence is common but not required.
I also agree with @MWollaeger that using the drivers and signposts and avoiding the Inciting Incident is a less confusing process. I think that Dramatica does this part better (and many other parts) better than anyone else.
I recently ask myself, by spending the time to answer a question or studying this facet of storytelling, does it help me develop a better process? If I can't say yes, I avoid thinking about it too much because... it is just procrastination in disguise.
It's just like buying 500 books on writing theory. In end, it is just procrastination. You are either writing or you are being a student of theory.
I think that writing is a crappy experience. Ninety percent of the time, I don't know why I try to do it. Maybe it gets easier for more experienced writers, but I hate it so far. But I'm not going to quit.
When I wrote screenplays, I hated it (I still write screenplays to use as a first draft for books; I still hate writing them), but I write 300 stinking words a night. It ain't much, but it is what I can do working 70 hour weeks.