Yea, saint leaf is a species of Ocimum, Ocimum basilicum, and Ocimum gratissimum to be precise. Both species are different in the size of the leaves among other physiological differences.
My wife uses it for cooking. It has a very welcoming scent and the plant is generally medicinal. I really do not know about the health benefits highlighted by the author, One thing I am sure of though is that aqueous extract of Ocimum works well against dysentery.