We have a term in my state for "not strictly by the books illegal"... it's called..... LEGAL! What that Q&A basically said is that police don't have the legal justification to arrest someone for open carry, but will do so on some trumped up BS charge. Police enforcing laws that don't exist is the exact opposite of what they were created to do. Betraying the very essence of law enforcement should be grounds for being fired IMHO. Especially when the officers KNOW they are not enforcing the law.
We had the same issue in my home state for a while. We had an entire town declare that open carry was illegal and would arrest anyone for open carrying. Ended up going to the state supreme court where the city was told they were violating state law, and to remove that law from their books or lose all state funding. Later they tried the whole "public disturbance" BS to do it, went back to court and still lost (probably because indiana doesn't have a public disturbance law).
Now, regarding law enforcement powers, different states may be different. But in IN, a LEO has to follow all the laws of his state, as well as pretty strict guidelines for anything she/he does. They have exemptions written into state laws about carry for instance, as well as breaking speed limits and traffic laws in the case of an emergency only. I showed the district courts ruling to three of my students last night, one was a lawyer, two were LEO's (one for 20+ years, the other for just over 12). All three said that if it had happened in IN, the officer would probably have been fired, if not brought up on charges. This was from reading the district court's ruling, not the more inflammatory article. So I think we're just looking at this from the blinders our own state justice systems puts on us.
Also, side note: Theft in IN is exactly what I said it was. Intent to convert property to your own use has NOTHING to do with whether it's theft or not. Depriving the lawful owner of their property or it's value (via destruction, loss, etc) counts as theft. So
Now, I personally think open carry is just plain silly, and won't do it at all except for one town I have to go to every now and then that REQUIRES open carry (ordinance passed before the state exemption laws took effect). It sounds like Mass LE is playing fast and loose with people's rights. Arresting people on some other charge for enjoying legal behavior? Denying a person a firearms carry license because of them following the law? Sounds incredibly UN-american to me.