However, the woman never said "a thousand dead children is a good sign." What she said, in essence, was it was a sign of the cartel's desperation, that they were being damaged by police/military activity.
Now we can debate whether that is actually true or not, or how significant it is, but in fact the stats on the dead kids doesn't really tell us much. We don't know how many of them actually died in cartel-related violence. We don't know how many of them were ACTUALLY "innocent children" and how many of them were actually, themselves, teenage cartel members, street dealers, runners, etc.
Salon.com kinda overhyped the whole thing a bit, imho.