First, a general question: the author says, "There are at least two good reasons why nasal cycling happens." Wouldn't it be more correct to say, "There are at least two good benefits to nasal cycling"? Because, what he does say, that implies that there are definite evolutionary selection benefits to nasal cycling, and that's a claim I'm confused by.
Second, people who meditate and use the breath as their meditation object are very clued in to the nasal cycle. I'm pretty certain that my meditation teacher, a Buddhist monk from Thailand, could exercise conscious control of which nostril he was breathing through. I reckon that shouldn't be possible, but there you go.