If I was to guess, I'd say that it would be along the lines of "You think Iraq or VT are bad? More people died every ten minutes in the Holocaust--for years"
The daily death toll in Iraq and the VT shooting have nothing to do with government instituted killing like the Holocaust.
Iraq and VT both reflect random acts of violence (even if the suicidal attackers put some planning into their targets).
It would’ve been more appropriate to compare it to genocidal purging in any of a number of regions. It could be said that if we do not offer some crackdown on the “insurgency” (which is NOT an Iraqi led resistance), the resulting government rule that emerges from the chaos could likely be oppressive to any of a number of religious minorities, including variant sects of Islam BY other muslims.