It's not "my" rule. I never asked for it.

Found the actual law: https://www.ncleg.net/EnactedLegislation/Statutes/HTML/BySection/Chapter_20/GS_20-138.7.html

It looks like what I heard before was just incorrect, the law explicitly allows sealed containers in the passenger compartment. Also, the commercial vehicle exception is to allow open containers.

Funny enough, if you ask Bing a rather pointed question about whether or not a SEALED container is illegal in the passenger compartment in North Carolina, it says that it is... misinterpreting the available sources like what appears to be many other parties before it.

Regardless, I do think it's wise advice to put it in the trunk whenever practical like any object that could become a projectile in an accident.