I'm casting my vote for irrelevant. 

For one thing, what does a sanctuary state or ideology have to do with what happened? Neither the killer nor his victims seem to have immigration issues and seems any "ideology" he may have had was there as an afterthought. He probably lacks the faculties to spell ideology let alone follow one.

I would call this a public health/public safety issue and suggest that mental illness be given the same official attention as any other category of serious illness.