Matthews, initially teasing a guest for using the word "lethal" in a discussion about recent poll numbers on the Wisconsin budget battle, chided: "In the media world, I think we all agreed...after the horror in Arizona that we weren't gonna...use ballistic terms." The MSNBC host then segued into a clip of Boehner making a gun reference, after which he railed: "What is this Glenn Beck talk?...That's how Glenn talks. 'I'm gonna put a gun to your head' and all this!" This led Huffington Post's Howard Fineman to tag in: "Well when John Boehner back slides, he really back slides."
However, according to Newbusters' own Noel Sheppard , Matthews, Fineman and most mainstream media outlets, other than Fox News, have been largely silent about the Hintz threat.
To review, a Democrat man cursing at a Republican woman "You're f-ing dead" isn't worth mentioning in Matthews' mind, but if you dare make a political metaphor referring to weapons (something Matthews himself has done)  that's objectionable.
(MP3 audio) 
The following is the relevant exchange that was aired on the March 1 Hardball:
JOSH MARSHALL, TALKING POINTS MEMO: They see that the Republicans, Walker, et cetera, sees that, that collective bargaining argument which is really what's being discussed right now is a loser for them and when you have these poll numbers that are 60/30, you know those are lethal for anybody in politics.- Geoffrey Dickens is the Senior News Analyst at the Media Research Center. You can follow him on Twitter here 
CHRIS MATTHEWS: Lethal? Did you say lethal? Because let me tell you who is using the word lethal. You know how we all agreed, in the media world, I think we all agreed a couple of weeks ago after the horror in Arizona that we weren't gonna talk about, you know, "shoot 'em up." We weren't gonna use terms, ballistic terms in the way we talk. We're gonna, we're not gonna say, "Mow down our opponents" or all that. We're gonna stop talking about guns in regular political discourse. Somebody didn't get the message!
MARSHALL: I don't think, I don't think that's in, I don't think that's in, I don't think that's in the same category. I think those, I think those kinds of numbers can be politically lethal.
MATTHEWS: Well no you're missing. Here's Boehner! I'm just teasing. I used you to tease into Boehner. I'm sorry.
HOWARD FINEMAN, HUFFINGTON POST: You got in the way, you got in the way of one of his set-up jobs.
MATTHEWS: You were part of my set-up sir. Let's take look. Here is John Boehner who didn't get the - you of course have always gotten the message - here is John Boehner on unions. And let's look at his metaphor. Let's listen.
REP. JOHN BOEHNER: In some of these states you've got collective bargaining laws that are so weighted in favor of the public employees that there is almost no bargaining. You know we've given them a machine gun and put it at the, at the heads of the, of the local officials and they really have been, had their hands tied.
MATTHEWS: What is this Glenn Beck talk? Guns at the heads of - that's how Glenn talks. "I'm gonna put a gun to your head" and all this!
FINEMAN: Well when John Boehner back slides, he really back slides.