Slander occurs when somebody says something about somebody
else which is damaging or defamatory. In this case there is no perpetrator of slander, there was a news organization who may or may not have made a good faith error in reporting. The First Amendment is broad in its shielding of journalists because Journalists rarely kill people (accidentally or intentionally) with their words, and because stamping on free speech (as you can be sure the NRA would do if it were permitted), would have a "chilling effect" on public and political discourse.
You may be wedded to the Second Amendment, but the First trumps all the others.
Now Bob Novak tried to put a woman in peril of her life, a serving CIA officer at that, and he got away with it, and I don't recall a lot of hand-wringing here about his deliberate actions. In fact I very clearly recall people here being angry that Valerie Plame survived his little passive-aggressive journalistic attempt on her life, because it revealed the sham that was the Sainted George W.'s WMD excuse for invading Iraq, which of course was thought to be a capital offence at the time.