C'mon, nobody can be that stupid.
They aren't stupid. They want people to die. They use the language to affect that end.
He knows very well she wasn't armed. But he wants to justify her death (because she was a gun owner, and therefore deserves to die) so he twists the language to make her appear to be the culprit.
It's just lying. It's not stupidity, it's lies. He wants to justify killing gun owners, and he wants to use the slaughter of 20 school children to further his belief that gun owners should be killed.
Progressives love it when babies die. Because the first thing they do is try to pin it on people who defend liberty; to justify further removing their right to defend themselves, their right to worship as they please, their right of free speech...whatever. Different tragedies trigger the attempt to remove different rights. Which is why you won't ever see them doing anything to actually protect people from being killed. It is always about finding more reasons to kill them....and using mass slayings to terrify people into submission.