I agree sending someone to jail over a single shotgun shell is a gross miscarriage of justice and perversion of the law. Committing a
second miscarriage of justice by sending a TV news commentator to jail does not make the situation better.
Now you have two people in jail instead of one. We should be trying to have zero people in jail who should not be there. We shouldn't say "Well, we put one person there for a bad reason, so we should put everyone else there for the same bad reason too". This is what you seem to be proposing. I get David Gregory doesn't share your politics, and maybe you just don't like him. That doesn't mean we should put him in jail just so you can feel better about some other person getting screwed. I doubt Irvin Nathan would feel any better about being in jail if David Gregory were there along with him. I'm sure he'd much rather just not be there.
Side note: You can look at actual data here - http://www.disastercenter.com/crime/dccrime.htm
The murder rate in DC was rising steadily since 1960 until the gun control laws were passed in 1976. It went down briefly, then exploded with the crack epidemic in the late 80s, early 90s. Obviously, there are many, many factors contributing to the murder rate and you can't control it by modifying only one input. I'm not trying to imply otherwise.