IMO, it makes sense.. Fatal is targeting in his line those who were "politically" targeted by the Twin Towers incident, meaning the US government, "the man", the "system", etc.. It's like many other rappers bashing "Bush", and talkin' about Bin Laden, like Mos Def and Immortal Technique in their "Bin Laden" joint where they say:
Bin Laden didn't blow up the projects
It was you, nigga
Tell the truth, nigga
(Bush knocked down the towers)
Tell the truth, nigga
(Bush knocked down the towers)
Tell the truth, nigga]
Although Fatal's line is different, it's pretty much the same meaning.. That he's against those who were politically hurt by the Twin Towers knockin', and who were responsible for it in the 1st place.
I dont think it's insensitive.. Well maybe a lil.. But i'm sure he wasnt targeting the "people" or the "innocents" with this line..