It is well understood that Holmes was wearing body armor. Why argue about the kind anyway? There is no point to it.The context is that Joan Peterson was discussing the "Batman" mass shooting. She was arguing that it was impossible for anyone to take him out as he was wearing body armor. Readers pointed out that no, he was not wearing a bulletproof vest. He was wearing a load bearing vest meant to carry gear which is about as bulletproof as a windbreaker. Clearly, reality does not impede on her world, however.
For Joan, "it is widely known" that he was wearing armor, so he was. The end. Just like "it was widely known" that the world is flat, or that the size and shape of your cranium affects your personality, and that astrology is a great way to predict the future.
News flash: If 51% of people -- or even 95% of people -- believe something to be true, that does not make that information factually correct. Facts are not subject to democratic processes. We don't get to vote on what color the sky is, or what the weather was yesterday, or whether a moon-bat lunatic was wearing armor or not. To think things work otherwise is plain and simple magical thinking.
This is why we don't have a democracy in America.
Addendum: Besides, so what if an attacker is wearing body armor? If you shoot someone wearing a vest they will notice. It is like getting hit with a sledgehammer or having a bowling ball dropped on you. Another CCWer shot an attacker bent on mass murder who was wearing a vest and drove him off. The goal is to disrupt the attacker's action, get inside their OODA loop, and stop their current attack. Once you've landed a hit -- even on a vest -- you can follow up with more, flee the area and break contact, move in to physically restrain them, etc. This is why we practice failure to stop drills, right?
I'm not saying it would be an easy shot. I'm just saying that even when confronted with direct factual evidence that challenges her worldview and does not even impugn her central argument (even I would concede that such a shot would be a difficult one with a defensive pistol, body armor or not), Joan Peterson is unable to change her mind.