I have my own business and a big part of my job is meeting clients and business owners on a regular basis. Because of my job Ive paid special attention to learning body language, behavior and speech patterns in order to not not only analyze the non verbal communication of the people in front of me but also to learn how to best project the image that I want to project.
Some of the things that the article say are true, BUT you can not generalize actions, and say they "always" represent the same thing. Holding objects in front of you "MIGHT" mean what the article says but you must have the intelligence to see the person in front of you and analize if he is really is representing shyness or if he IS JUST FUCKING HOLDING THE CUP IN FRONT OF HIM! because maybe its just comfortable.
Im constantly analyzing the people Im meeting to give a better presentation but I dont analyze details like this, I analyze the entire behavior of a person, or their level of comfort, speech, eyes, those type of things give you a better idea, yes I do analyze details but I dont think they are a big indicator because like I said sometimes people take postures for many other reasons and not exactly for what the articles says. Their office, their desk, their clothes and especially their behavior are a much better indicators of how a person really is than small postures. Peace!