My take on this is, the police told them they were illegally carrying, yet didn't arrest them. Sounds to me like the police most likely knew it was legal but wanted nothing more than to make them leave public grounds, possibly to keep down any fear from the public
Also, on the increased training part, just how much effort is needed to explain to your underlings that something is not illegal? I would have expected them to be knowledgable already, first and foremost, about open or concealed carry.