Gun Dealer criticized harshly for going to Virgina Tech to speak

The Question is what exactly is a sellers moral and ethical responsibility for the misuse of a product sold.

The name of the licensed gun dealer who sold the gun to the Virginia Tech killer is
Eric Thompson. He has been criticized harshly and even labeled ethically challenged and insensitive. Some interviewers even went as far as to say he's irresponsible for having went to Virginia Tech to speak this last past April.

Some school faculty, parents and relatives of the victims of the tragedy have denounced him. The criticism opportunistically turned in to anti-gun advocacy.

People I need comments and thoughts on this.

By Apropos