There has been a huge effort made to hold firearm companies accountable for tragedies when their firearms are used inappropriately. A firearm is only as deadly as the person's intentions who wields it. Set a loaded firearm in the corner and there is a zero percent chance it will get up and shoot someone. So, the question becomes more about mental health and personal responsibility than anything else.
Trying to hold these companies accountable is nothing more than an extension of gun control. There are those in this country who seek to eliminate the second amendment by any means necessary. Holding these companies liable for the misuse by an extremely small population of legal and responsible gun owners is like shutting down a fast food giant for making people have heart attacks.
Everyone has the freedom of choice. In their personal lives, they are granted this freedom and most use that choice properly. There is a much deeper issue at hand than a person with a gun. Anyone bent on destructive action will likely carry this out regardless of what weapon they choose. Identifying and getting those people help should be priority number one!
We live in an ever increasingly violent world. Acts of aggression are commonplace in big cities. Everyone strives for this vision of a peaceful world all while keeping an eye of reality over their shoulder. We focus on the wrong issues while the true problems never seem to be acknowledged. We hope someday eyes will open and these issues will be resolved definitively.