I agree with the last part of your post. But even disturbed people usually want to have their voice heard. It would be unusual for him not to have left some indication of his hate or anger at the world.
Especially a 20 year old. They are born with them attached to their umbilical cord.
There is video of him confronting Trump people and he sure screamed like a banshee at them.
He could have even had a burner phone.