Why abduct a guy and force him to do IT work. It's not like there is a lack of skilled people, that can't be bothered with moral/legal questions about who their employer is or what they are doing. If there was banks, mpaa/riaa, phone/cable companies, etc... would all having to abduct IT staff too.
There is a lack of skilled people that will work for free, require no benefits, who you can make sure will not carry your secrets to their next employer. It was suggested that they could have actually sent gang members through school to learn the same thing, and while that would take a pitiful amount of money for a loyal employee, it would also take years. If the cartels started sending people through school when they had started setting up their own networks, those people might just be graduating by now, which would be too long to wait in the cut throat business of Mexican cartels.