Sounds like some of his writings were anti Catholic, some were antisemitic, and some were anti Trump. Seems to be the thoughts of a person who was deeply disturbed- in other words, ripe for being told they were trans. You know, easily coerced- to push a narrative.
Tell that trans person they're being attacked and going to be eliminated- maybe even have the Lt Gov of Minnesota show of a shirt with a weapon inferring trans need to fight back.
Not hard to see how you get to this scenario. Just like so many of the last several school shootings.