It says he "participated in a discussion that touched on using it to evade economic sanctions."
His defense is that "his presentation contained basic concepts that could be looked up online."
Since this is all I see in the article, it really looks like a somewhat ignorant prosecutor over-reaching. Unless there's some significant part of the story being left out, I can't imagine he goes to prison over this.
The fact he actually travelled to North Korea to give said 'presentation' makes it likely he gave them more assistance. Helping a country evade sanctions is a crime in the US, so dunno what he thought would happen.