I have serious doubts on the validity of this story. I don't believe for a minute there was any LE sting.
Nobody who is not wearing a tin foil hat would ever believe that this was a LE Sting. Even the most incompetent LEO in the USA would understand that this would be entrapment and that it would never stand in court. It would require the straw buyer to approach the "bystander" and freely ask for them to assist in a purchase, with that "bystander" being a LEO for it to be a good case. The chances of this occuring "freely" approaches zero.
Media sting... probably not.
Poorly socialized nutcase trying to be helpful? Most probably.
"When I hear hooves behind me in Arizona, I think horses, not zebras"
The simplest explainations are usually the right ones.