> It's fairly clear what the cause of a mosque shooting is: Islamophobia
Very sloppy thinking. Islamophobia is a phenomenon, but it is not a philosophy (Or if it is, it is an extremely sloppy one). Nevertheless, it seems wild to claim that Islamophobes of the west (typically, white, pagan/atheist, alt-righters, etc) share much common ground with Islamophobes of Asia (for example, the Chinese government, or radical Hindus).
If you want to understand why all these groups turn out Islamophobic, it's worth studying their motivations, and they are different. For example, China's motivation is a general antagonism towards all religions and a distrust of religions such as Islam and Christianity that purport a higher power to which the state is subject. On the other hand, the neo-Nazi motivation is simply that Islam is not their religion, thus Muslims are evil. Conflating the two and attempting to construct intervention programs based on the other's motivations is an exercise in futility.
EDIT: For example, after reading the manifesto, this shooter is islamophobic because he thinks overpopulation is killing the planet and muslims have more babies than white people. That certainly requires different de-radicalization than someone who thinks Allah is a false god that ought to be replaced with the Christian one.