I liked that article. However, I would like to point out that Angel's curse wasn't that if he experienced one moment of pure happiness he would lose his soul; rather, according to Jenny's uncle Enyos, the curse was that if he forgot for even one moment what he was and what he had done over the years of his unlife, he would lose his soul and Angelus would be unleashed again. The orgasm was just incidental, since Enyos already told us by that point that Angel's pain was lessening just by being with Buffy.
It's just easier to say 'if he gets a big happy, he turns evil'. But it's not quite that simple.