Throw my hat into the fray. I disagree with the article. I work in private security. We do overt and covert work. Applying a logic that walking in with a visible gun will deter criminals from their plan is a huge assumption. Most self defense scenarios are very fluid and your firearm is a large variable in these scenarios. Having a passive exposed oc does not give you options. Instead it pushes a narrative that the gun is a warning sign to poorly planned or uncommitted criminals. Huge wrong blanket assumptions
Except when Dr. John Lott interviewed criminals in prison, exactly what he found was that they almost always picked easier targets. When confronted with a "hard target" someone who the criminal knows is armed, they will seek easier prey. Based on that, I believe the deterrence factor is a thing.
I believe his research is in this paper: