The complaint does spend quite a bit of time trying to establish what took place was an actual 'technology transfer' and his intent to violate sanctions in some way beyond merely traveling and ottering there. And the charge itself is conspiracy, with all of the extra bits they have to show for that attached.
I have zero expertise in this beyond nerdgooglery but the fact this dude's previous adventures seem to have included bananas shit like 'running a web-to-tor gateway and trying to sell the logs to governments' makes me wonder if there isn't more to this that's even dumber and worse for him.
Equally bewildering are the motivations and intent of the North Koreans. Surely if you actually want someone's actionable insights on violating sanctions, you're not going to do it in public at a conference. "American expert declares cryptocurrency use to circumvent imperialist oppression promotes peace" might be all they really needed from him. It's a cliché but 'useful idiot' seems kind of plausible, with quadruple emphasis on 'idiot'.
It is a truly weird set of circumstances. If he could plausibly have claimed not to know about the sanctions, this would be a harder case for the DOJ, because the statute requires willful violation. But if the complaint is accurate, Griffith did essentially everything he could to wreck his defense. We'll see, though.