The big drop, which began Aug 15,
What chart are you using? As I said, on Bitstamp I see only a small $5 drop on that date, like those that happened almost every day in the preceding 2 weeks. There was another $5 drop the next day (Sunday), and no drop on the 17th (Monday). The big drop was on Aug 18.
How many bitcoin traders took note of that post?
It seems that we have very different ideas about who are the "bictoin comunity" and how they think. Regular readers of the bitcoin forums seem to think that all bitcoiners and traders are also regular readers like them, well-aware of issues and developments. But I would be surprised if, even today, there are more than 10'000 bitcoiners who are aware of the "block size war" and have a reasonable idea of what it means. I even bet that most bitcoiners could not tell Gavin from Luke or Peter in a police line-up.
Among those bitcoiners who do have minimal understanding of the war, I bet that many think that it is an minor technical question that will be satisfactorily resolved, like all previous issues were, and therefore it is not something that they have to understand further.
FUD indeed... That obviously fake email was a low point in certain party's struggle for absolute power over Bitcoin...