This is actually a really good point.
There's a lot of faces in the crowd who don't seem particularly happy to see JFK. If the umbrella thing was so well known why was there only the one.
And why is it that the only man with an umbrella is fabricating his HSCA testimony? If that doesn't make the Umbrella Man suspicious I don't know what does.
But nobody here, not me in particular, said that it was a well known symbol of appeasement in Dallas (or anywhere in the US) at that time. So it's not surprising that only one person used it that way. My posts were in response to the original poster, Michael Griffith, and his claim that it was "absurd" that anyone would use the umbrella as a symbol for anything in protest (as Witt claimed). He said he never heard of its usage for such things.
But the links I provided show the origins of this symbol and how it came to be seen as a sign of appeasement in the UK in particular or weakness politically. In another link there was a story about some German students sending JFK umbrellas as criticism for his lack of response when the Soviets constructed the Berlin Wall.
There was nothing in the links about how popular the idea was and/or whether the Birchers/Klansman in Dallas (or elsewhere) knew that it could be used to heckle JFK because of his father's support for the appeasement policies of Chamberlain. Some people knew about it; but most probably didn't.
Apparently Witt knew something about its symbolism. As he testified:
Mr. GENZMAN. Why were you carrying an umbrella that day?
Mr. WITT. Actually, I was going to use this umbrella to heckle the President's motorcade.
Mr. GENZMAN, How had you gotten this idea?
Mr. WITT. In a coffee break conversation someone had mentioned that the umbrella was a sore spot with the Kennedy family. Being a conservative-type fellow, I sort of placed him in the liberal camp and I was just going to kind of do a little heckling.
We have Witt himself says he vaguely knew about the symbolism and how it was a "sore spot" with the Kennedys. So he decided to just heckle him with it. We have one person doing an odd thing. And LBJ knew about the symbolism too when in the campaign he directed a criticism at Kennedy Sr.
Y'know, not everything has to be jammed into the conspiracy against JFK? Sometimes a guy scratching his nose in a photo in Dealey Plaza is not a signal, it's just a guy with an itchy nose?