This father is in big denial. I’m sure he is just looking at it from a practical standpoint. If he had no guns he would not have been able to shot anyone. Well yeah. That is a no brainer. How about talking about his son’s mental state and how that contributed to the situation. Better yet, talk about how you were never involved in the boy’s life so any possible positive support you could have provided was not there. Maybe your response is a reaction to the fact that your failure as a father played a huge part in his loneliness and lack of self esteem.