A friend and work colleague of mine has been diagnosed with tuberculosis, when I took him to the hospital because he was having problems breathing. He had been earlier (falsely) diagnosed with pneumonia. He says I don't need to worry about it because his doctor says he has no "expectoration", and he isn't planning telling anybody when he gets back to work. We work in a crowded open-space/office environment. Is it true that tuberculosis without expectoration is not contagious at all?
No, it's not true according to the CDC.
The TB bacteria are put into the air when a person with active TB disease of the lungs or throat coughs, sneezes, speaks, or sings.
When you speak you force air out your lungs, and presumably some bacteria can be carried out in this fashion.