The bastards have talked about this before,

so no surprise.  Neither is this:
'The use of poisons of chemical and biological weapons against population centers is allowed and strongly recommended due to the effect on the enemy,' explained al-Awlaki. 

Two things:
One is that PC-brained idiots, when these are attempted, will try to turn it into "Muslims in fear of backlash!"

Two is that a lot of media would do anything possible to downplay the chance of terrorism in any fires they do set(see 'PC-brained' above).