Engadget links to their "source", and their source doesn't link to anywhere they got the info from.
They say the workers were allegedly working 120 hour work weeks... if my math serves me right, that is 5 straight days and nights without sleeping. I don't think that is humanly possible in a 7 day week, even under slave-driven conditions such as described in the article.
Also, it sounds like, from the article, that the workers were hired as contract workers from India, then flown in to perform a contract. If that's the case, their pre-agreed wage in India would be fine imho, and easily confused with local laws (no intentional malicious intent), and perhaps why they weren't fined more heavily here in the US.