I don't want to get into too much detail on this out of respect for Otto. I wasn't there when he took the poster down, but I definitely believe that he did.
Also, no invisible lines were crossed - we were told very specifically before arriving in NK by the tour company that under no circumstances should we go to the staff-only floor of the hotel and that people had gotten in trouble for going there previously (it's moderately infamous). My memory of that is hazy, but it may even have been in response to a question about that floor from Otto. As I said in another comment, I really don't think that the NK government is interested in oppressing tourists for no reason.
That's how these things always go (15 years is the usual "sentence"). Assuming that the US is willing to play ball, they'll start negotiating now and eventually trade him for a visit from the director of the CIA or some rice or whatever. AFAIK no American since the Korean war has actually served a sentence from the DPRK.
Also, no invisible lines were crossed - we were told very specifically before arriving in NK by the tour company that under no circumstances should we go to the staff-only floor of the hotel and that people had gotten in trouble for going there previously (it's moderately infamous). My memory of that is hazy, but it may even have been in response to a question about that floor from Otto. As I said in another comment, I really don't think that the NK government is interested in oppressing tourists for no reason.