He might have figured the flash drive was more sensitive an instrument than his body.
Or maybe he just figured he didn't care what happened after he died.
Maybe he thought the way hitler did. If he was to die, they could all die.
I get the distinct impression some bio or chemical are about to be un-sanded real soon.
He probably figured that either it would be destroyed with him, as you stated, or that if he was on the run or in a shootout, he would have a few seconds to destroy the thing.
I don't think he'd anticipated being bombed and only having the breath knocked out of him, to put it lightly. =P
In this case, we executed it exactly right. The bomb did its job in killing him (in a long, painful death) AND left behind enough evidence to round up 800+ terrorists (in only a week!).
Good work, boys!