The following is cynical and may cross the line into paranoia. I know nothing about this particular incident, but: (1) Wilmington's new police chief comes to us from NYC via Chicago. (2) In Chicago, he got pretty well known as the CompStat guy. (3) If one has the typical NYC-Chicago police brass / press view about guns, then one is likely to think that "taking guns off the street" is a high-priority goal, and that guns is guns, regardless of who (other than cops) is carrying them or in what manner. OC'ers, drug dealers with long rap sheets, it's all the same. (4) It is much easier for CompStat-type systems to measure progress in "taking guns off the street" by counting arrests and administrative confiscations of weapons than to measure that progress by counting actual convictions for actual crimes. Ergo (5) one simple way to show progress in crime-fighting is to arrest people for gun possession without caring too much about whether they were committing crimes or not. The arrest juices the statistic whether the "bad guy" walks because of some b.s. technicality or because he was actually just a normal citizen lawfully carrying for his own protection and not doing anything illegal.
Moreover (6) the gun-hating press will, out of stupidity and/or malice, never notice the foregoing strategy (or numerous other ways to manipulate the CompStat system to show "progress" that doesn't actually make the city a better place to live), and if they do, they will argue that it's both The Will Of The People and obviously necessary for public safety.
Add all this together, and we should all consider the possibility that we're in the process of becoming low-hanging fruit for the CompStat method.