I think the article is using the wrong stereotypes here, for "masculinity and machismo" are terms applied better to Metal's parent music; that is Rock 'n' Roll in all its forms. For example, Rolling Stones' "Under My Thumb", tons of sex-drenched Aerosmith songs, the sleazyness of New York Dolls, AC/DC's "evil" double-entendres, etc. "Sex, Drugs and Rock 'n Roll", the music's main goal and topic. 
 Where when we are in the realm of heavy metal, shouldn't the two key words be darkness(or dark spirituality) and rebellion in general? (Black Sabbath, Budgie, Sir Lord Baltimore, Uriah Heep, Blue Öyster Cult, Scorpions, Rainbow, Motörhead, Judas Priest, UFO, Riot). Also, most of these bands - while rooted in doom, fantasy, social flaws and individuality - made a few deep love songs and introspective topics as well. About "satanism" I think it should be emphasized, but not generalised. Although Satan, Lucifer and anti-Christian topics are very frequent in past and modern Metal, we shouldn't forget about the pagan, viking and babylon-obssessed metal bands who are also out there in many numbers. One thing we could say is that most Metal finds inspiration in religion or the occult. 
 If anything, "machismo in metal" should be referring to the glam metal/thrash era, where sleazy misoginy and aggression was a main trait of the image of these emerging subgenres. For a blunt example, the machismo reaction to war would be "Let's go fight these bastards and destroy them", am I right? So then we have Heavy Metal, who from it's origins talked in brutal words AGAINST going to fight politician's wars. How does that make Heavy Metal "machismo"? To me, the music seems more intent on bringing up "taboo" subject matter, and not to vent masculine might.