This is a classic example of Reactionism heading toward unconstitutional action. As is often the case, this man's reactionism is driven by the murder of a loved one, and as is also often the case, the cowardly murderer killed himself rather than being brought to justice in a court where he could be confronted by the grieving family.
There is no doubt, that this man's anger and frustration are understandable and that he deserves sympathy.
What he does not deserve, however, is a special status in the determination of others' constitutional rights.
Andy Parker has turned his anger into a mission, and since he cannot make that mission be to convict his daughter's murderer, he has made it a mission to take the rights of law-abiding people. He wants a misguided justification for a senseless, evil act. And the media is complicit.
Look at the article from Time on the anniversary of the murder of his daughter. It is full of emotional content and photographs of the slain. It has profound-sounding statements of commitment by Andy Parker. And it has the following three sentences as the sum total of his mission for gun control:
"...pledging to keep fighting for gun reform in the name of his 'fierce' daughter."
"Parker's parents have become vocal advocates waging a campaign for gun control legislation. The news reporter's father recalled how his grief turned to anger which then turned into a 'rallying cry' for an end to gun violence."
"his 'conviction' won't waver' in his attempts to secure legislation."
Does Andy Parker think he can end "gun violence?" What legislation would do that short of confiscation of all guns - which would be unconstitutional. Perhaps he wants to take gun rights from people who don't act "normally" (as opposed to criminally). That, too, would be unconstitutional. Maybe he is looking for a type of "pre-crime" unit to stop evil before it happens. That didn't work in the movie, Minority Report, and was even shown to be immoral (and would be unconstitutional by way of the 5th Amendment in addition to the 2nd Amendment).
No one makes good decisions in grief or anger. And long-held anger turns to bitterness and hatred which are not drivers for sound action, only for revenge. That's reactionism and it has no place in American rights.