The SS190 AP loading of the 5.7x28mm cartridge, about which several in the media are prattling on as though they knew from which end of the weapon the bullet emerged, is not just "restricted", but actually illegal to import for any use but law-enforcement or the military. To the best of my knowledge, it cannot be purchased from Joe's Police Supply Co.; it sits in a customs-bonded cage at Fabrique Nationale's South Carolina facility until an order comes directly from a government agency. So that's not what was used at Fort Hood.
Further, unless your target is swaddled in Kevlar, the "super-scary cop killer" bullets are probably less effective than the plain vanilla kind.
Basically, even bringing it up is a red herring. Doc Jihadi could have done every bit as much damage with just about any pistol.