The world has only a small supply of suicide bombers. If they were all living together, they'd make for a very tiny town.
As in, everybody would know each other because the town was so small. So it isn't surprising that there aren't very many suppliers of equipment for that community.
Oh, I wasn't surprised. :-) Just hadn't seen that fact in public. Although there are a lot of freaks and independent whackos out there, when you start examining focused, resourced terrorist acts the community does become much smaller. (But still way too big for my comfort zone!)