This article is more hyperbole and spin by a media trying to make this solely about race.  Minnesota is not  a "must declare" state meaning that Castillo had no reason to tell the officer he was armed unless directly asked.  By declaring he had a firearm he unknowingly escalated and contributed to an already tense situation becoming more tense.

When I first got my permit I thought that I was being "responsible" if I told the officer or handed him my permit with my license.  I discussed this with an officer friend of mine and his response was surprising.  He said he assumes everyone is armed so he couldn't care less about my CCW.  He also said that while you may be talking to him at your window you don't  see his rookie partner coming up on the passenger side.  The nervous rookie doesn't hear anything but the word "gun" and then who knows what happens next.  Its best to just keep your mouth shut until asked.