Well if you haven't noticed the Five Families are his focus. He doesn't cover any of the other Families except for DeCavalcante and Philadelphia but it's rare. He has mentioned the Ndrangheta in articles before when they've been linked to a Five Family bust.

A reason why more news articles don't cover the Ndrangheta busts is the same reason other criminal groups don't get news attention it's because no one cares. LCN was massive in American pop culture from Valachi's testimony being live on TV, the Godfather, or John Gotti reveling in the media attention everyone knew what it was. The popularity has died down but there's still a big interest among the American public. But the Ndrangheta isn't LCN and isn't well known so the only time they get media attention is when they're connected to an American Family.

The feds barely have anyone investigating the Five Families so you can assume the Ndrangheta isn't on the top of their list. When we see Ndrangheta members or associates arrested in the US its almost always from a bust linked to one of the Five Families or originated from an investigation in Italy like the recent one in New York.