- I'll hack hundreds of these underfunded school districts

The idea that you, or the mob would hack any school district, let alone "hundreds" is dubious. Precisely how? From one school district to the next, you'll have what to hack? What degree of variety would that involve in terms of the diversity of systems. Systems that are already hardened to withstand the pranks of script kiddies?

And where to start? All of the small towns first? Distributed geographically, and with varying connection speeds? And none of them have any level of intrusion detection, or malware defenses at all? I suppose you'll spear phish thousands of school staff members and no one will notice that, and surely it has nothing to do with witness intimidation.

This assumes that all witnesses have children. What if they don't?

Also, keep in mind this was in the 1960's and on into the 1990's so, computers then, were not what they are today. And since the 80's the mob has ceased to be what it was back then, for the most part. Now, really, it's gangs and drug rings, moreso than the mobsters being busted prior to the 90's.

- watch for kids with identical grades

Uh, right. Not really. Identical? How does that work, when the teachers are different? Why would you assume performance would be equal during a massive distracting disruption to one's life? Even "statistically identical" (if that's even a thing, though I doubt it, when it comes to public school grading systems) is a stretch.

- parents have no credit history

Okay, how is that going to shake out? So, assuming you've "hacked" your zillions of "school districts" and now the subset of children have parents, you'll run your free credit report on all suspicious families? Okay, I guess... I mean sure... and then no credit history for some. Except there's still this thing with the school records. Combing the earth for people with no credit history doesn't sound realistic unless you can narrow the search to less than one hundred specific targets. Anything above that number sounds silly, and would draw attention.

- use the intersection of all their first initials

Probably the only part that holds water. Except you're operating based on knowledge from the article that you've benefited from, so this gets eliminated, because as an outsider, you wouldn't be able to assume awareness of this detail. You might notice it, after the search has narrowed, but without having this knowledge in advance, I doubt it would be useful information.

- same age for children and same-ish age for the adults

Yes, you'd be able to use this.

- they give them a digital presence

Doubt it. These are people who know all too well how wire taps work. Doing this for a protected witness would be profoundly stupid. Contrary to popular belief, life after the internet does still exist. Sacrilege to say such a thing on HN, I know, but it's true. I can feel the wrankled eyebrows from the other side of the internet as I type this.

- including a credit history

I think they said in the article, they do not do this. At all. The point being that this would be government intrusion on private business, severely complicating matters of fraud investigation, and more. Even now, today, in 2015 there are people completely without credit history. And so what? They can't buy a house or a car or maybe a luxurious high-end cell phone financed with a contract? Honestly, these are minor details in a small person's life.