Here is The "Canon" IMHO On WHY Brett Said "Right" !

FROM THE COMPLETE ALIEN OMNIBUS VOLUME 1 A L I E N Brett was only listed as an engineering technician. That was a fancy way of saying he was just as smart and knowledgeable as Parker but lacked seniority. The two men formed an odd pair, unequal and utterly different to outsiders. Yet they coexisted and functioned together smoothly. In large part their success as both friends and coworkers was due to Brett never intruding on Parker’s mental ground. The tech was as solemn and phlegmatic in outlook and speech as Parker was voluble and volatile. Parker could rant for hours over the failure of a microchip circuit, damning its ancestry back to the soil from which its rare earth constituents were first mined. Brett would patiently comment, ‘right.’ For Brett, that single word was much more than a mere statement of opinion. It was an affirmation of self. For him, silence was the cleanest form of communication. In loquaciousnesslay insanity.