School shootings or even shootings of public figures in public settings can often be blamed on nebulous things despite evidence to the contrary.
If someone goes to the effort and breaks into a public figure like Nancy Pelosi's house, which undoubtedly has more security than the average person, and beats her husband with a hammer, it's really hard to spin that away as being because of some nebulous other reason.
Put another way, if you are breaking into Nancy Pelosi's house, screaming "Where's Nancy", and end up beating her husband, there's little reason to believe it isn't political.