Have you ever tried to kill a harddrive with a magnet? It basically requires passing a rare earth magnet closely over the platters several times before the data is reliably damaged and if they had that kind of magnetic fields it would cause much bigger problems. And while I don't know to much about the properties EM radiation, I believe that magnetic fields don't interfere with radio waves.
My guess is that its the steel beams themselves are causing interference with the phones, that they incidentally had hdd failures (they have lived there for like 6 years), and the the steel beams have slight magnetic field because a small amount of current is passing through them (electricians like to ground to steel beams instead of running a ground line back to power box and putting to ground their) and they blame that weak magnetic field for their problems.
This is all purely speculation because they don't give any real details about the field.
It is called 'terrorism' and not 'demolition' for a reason, and I think that some fair sized bomb going off at about the same time at the capital and pentagon would cause a fair bit of terror.
Besides, I don't think you appreciate how big of a boom a couple pounds of C4 cause. The 'high' in 'high explosive' isn't a marketing term.
Function reject.