Jason Zengerle says that the idea of betting on an outcome like the discharge of a gun at another human being is "offensive". Well, I'm betting on good behavior, which doesn't seem that offensive to me. Zengerle et. al. are the ones claiming that people openly carrying guns have a significant probability of hauling off and shooting someone for no good reason.
I find that rather offensive, given how little the people saying this sort of thing actually know about the protesters. They may, to be sure, be gun-mad lunatics dying for a chance to shoot some random stranger. Me, I'd expect the gun-mad lunatics are probably carrying their gun concealed somewhere on their person, the better to use it without being stopped. But I don't know. The point is, neither does the other side. All these confident predictions of impending violence do not, to me, seem to rest on much more than the belief that people who openly carry weapons near a rally must be gun-crazed lunatics who want to intimidate Democrats with threats of violence. This is somewhat circular to say the least.
Zengerle also conflates this with presidential assassination, as have many other commentators. As far as I know, only one chap has been near the president, and he was a publicity stunt. The others seem to be at less august meetings. If a gun nut wants to assassinate a minor Senator or Congressman, he doesn't need to carry a rifle to a protest somewhere. They're not that well protected. And also, not that frequently attacked.