The reasoning for the shooting is pretty clear. He told his transgender lover that “I had enough of his [Kirk’s] hatred. Some hate can’t be negotiated out.”
https://www.documentcloud.org/documents/26098852-tyler-robin...
https://www.documentcloud.org/documents/26098852-tyler-robin...
What in his upbringing led him to believe the way to handle the situation was with violence is unclear.