If the security conference was in a place sanctioned under the US International Emergency Economic Powers Act, then yes.
He applied for a travel exemption, and was denied. He went anyway. He was charged with that, not the speech. That's how its enforced, for this specific reason. Regulate the intermediary to control the desired behavior. Don't regulate the individual with first amendment rights.
What piqued my interest is that why don't the NK held the conference in place like CN, HK or Macau? Pretty sure they can hook up more talents with much lower risk.
Ermmmm not here. When you can afford to tango with them, they don't take surprising constitutional views actually. That part is in your favor. Its more about affording to get that far, in other cases. This case isn't one of those? He wasn't charged for the speech, he was charged for violating a travel and business sanction after explicitly asking for an exemption and being denied. He went out of his way to hop over barriers placed by the government, and got charged for hopping over after telling the government he was interested in hopping over. They watched him hop over, they didn't charge him for the speech he gave after hopping over. Hopping over isn't a constitutional right.
It is absurd to think that a government (armed group with a pretense of authority) can restrict your freedom of movement like this justifiably. Your individual sovereignty and agency is violated.
Yeah, if he had been willing to take this to appeal we could find the limits of these government powers. But he took the plea and is going in the slammer.
Freedom of speech is meant to preserve democracy domestically, not be a free for all to aid enemies for profit. Any sane state, including free democracies, would prohibit residents from teaching rogue enemy nations how to avoid sanctions.
I do not think that this is a widely held view. Regarding the US constitution for example, Part of Bernstein v. United States was the complaint that DJB was not able to legally talk to or teach about cryptography to cryptographers and students that are not US citizens. As for the "freedom of speech" as a general concept, I think that it is more of an individualist than a collectivist principle. It does not refer to countries or groups by itself, it is the right for entities to speak freely.
He applied for a travel exemption, and was denied. He went anyway. He was charged with that, not the speech. That's how its enforced, for this specific reason. Regulate the intermediary to control the desired behavior. Don't regulate the individual with first amendment rights.