Maybe you could take it in a lighter fashion though
So because they are terrorists you think they wouldn't buy vB3? Pffh... If they use a pirate version they draw attention to themselves - While a large act of terrorism will, yes, draw attention, up until they commit the act, they want to remain as inconspicuous as possible, to avoid possible attempts to foil their plans - Therefore it is not unlikely that they purchased vBulletin...
Aside from this - Why should Jelsoft refund anything or donate anything to the family? Should Microsoft give something to the family for allowing the terrorists to use a Microsoft Operating System? Should Dell or Packard Bell or whoever made their machine components give something to the family for allowing the terrorists to operate their computers?
Answer: No.
If I were a terrorist, just because I drive a Renault Clio, doesn't mean Renault are responsible for what I do with it - Nor does a terrorist using vB3 mean Jelsoft has any responsibility for what is done with it...
Satan