Chiri is obsessive compulsive to the max. She'd only go school shooting if she saw someone on tv do it half assed to show how to do it properly to all the people who plan to.
Kafuka is such that only the evilest of evil can see the positive in everything. And she does. She'd clue right in to Chiri's bowling for zetsubou as her doing a favour by being a role model for all the would-be shooters who don't know how to do it. Then she'd say that it would benefit unrelated parties like Japan's military come up with military strategies and defenses by watching how Chiri does it and would convince everyone that Chiri is a national hero and get her off the hook.
Actually, they'd make great partners in crime.