what he's essentially doing is aiding/abetting.
So in-person talks is aiding and abetting?
What about videoconference?
What about emails?
What about a semi-hidden webpage meant primarily for them?
Or how about a general developer FAQ that would get anybody dev-minded up to speed?
Where do we draw this line of "aiding and abetting"? Material good? Information? Congratulations? This appears to be strongly a 1st amendment issue of speech. Not that I like NK, but that point is a distractor. Why is it a crime to talk about cryptocurrency and monetary censorship of countries?
Any act that would provide material assistance is sufficient. Criminal law is pretty liberal about what constitutes an "act" in furtherance of a crime. If it concerns you, stay far far away.
But merely publishing information in a book or on a publicly-accessible website for all to see is not generally going to get in you trouble (subject of course to copyright, publishing classified information, etc.).
They Tried that, but that pesky 1st amendment got in the way. Research the CyptoWars (which is seems are heating up all over again) and the PGP Source Code Book.
The US Government has been attempting to censor speech for as long as it has been in existence. the latest attack on crypto by the US Government for "national security" reasons is just the latest in the long line of abuses
The answer to "where do we draw the line" is that all the things you describe would be aiding and abetting if a jury would be convinced that you did it with an intent to aid them.
If you write "a general developer FAQ that would get anybody dev-minded up to speed" with the intent to help general developers everywhere and DPRK uses that, that's okay; but if you write the exact same FAQ content with an intent to help DPRK get that information because you figure out that just sending it directly in an email might be too visible, then that would be a crime, if intent can be established - based on e.g. your earlier communication and writings.
It's a prohibition on trying to achieve a specific result, not on a prohibition on any particular means of achieving that result.