Their objective is to terrorize the population.
Nearly all of Kenya travels via buses of various sizes at one time or another.
You can be the "B-team", the waterboys or the cheer leaders of jihad but if you succeed in terrorizing people then you have accomplished your objective.
This is not the latest CG Hollywood blockbuster trying to win a special effects Oscar, not is is a bunch of Darwin Award wannabes and their skateboards on YouTube seeking style points. These are maniacal killers.
The blood of infidels is all that matters to them. Infidel warriors, police, shoppers, bus riders, school children - it makes no difference to these jihadist scum.
Pure evil. And no one can, or will, stop them.