This is a lousy situation. I don't think that threatened beheadings in Kenya will affect transit ridership elsewhere, but just imagine if something like this happened in the U.S., Europe or Asia. In South Los Angeles, the Blue Line is already something of a death trap (intentionally at times, it seems), but I can't imagine gangs putting a halt to ridership through threats. In Kenya, many people have lost their mobility and are suffering economic hardship because of these threats. What should the Government of Nairobi or Kenya do to ensure a minimum level of mobility for it's citizens? What can it do short of meeting the demands of the group making the threats?
Of course, in Japan you could imagine that someone who rides this train daily might make anonymous threats to get a bit more space on the cars.