Certainly bluntness with clients can be unwise but our relationship here is not a client relationship. It is hopefully a friendly relationship. You may not be aware of this but USA men bond by insulting each other. Even professional relationships, while not insulting, can be quite blunt when the parties know each other.

You are sensitive to the cultural perculiarities of the Arabs to perceived insult and you would alter your responses accordingly. Shouldn't you try to be sensitive and understanding of the USA cultural tendency to be blunt? Of course it works both ways but it seems that the party that best understands the quirks of the other side has an advantage in the discussion. Try to think of it in a humorous vein and even try to respond bluntly sometimes. In client relationships we are taught that to use the vernacular of the client is a good tactic to win them over.