This article is great, super information sense, doesn't try to spin a narrative, just investigates the facts.
I find it crazy that as a system this guy of all people managed to slip though the cracks. An autist with Hitler's signature tatooed on his arm, combined with arrests and jail time for stalking and harassing women, and nobody thought to give this guy the mandatory anti radicalization treatment? Kind of insane. Lots of holes in the Swiss Cheese model.
On the other hand, what could have been done? The guy had no social support network, no family that would have taken care of him. You can't force someone to have friends, or to get them to take the prerequisite steps to overcome whatever might be holding them back. Getting rid of X? Maybe that would help things in aggregate, but I'm and optimist and believe that people are smart enough to no be racist just because their feed is.