From the trip info exclusions list someone posted for TAR 26, (there's a picture of that extended clue somewhere- it was something like a Thailand-Germany leg) Air Koryo/North Korea was indeed a no-go and I suspect for more reasons than not being able to get a transit visa on arrival.
I wouldn't be surprised to see any Israel concerns coming down to someone accidentally getting an Israeli passport stamp, and that can apparently cause problems if you're entering or transiting the UAE. Seems like more seasons than not at least require a connecting flight in Dubai.
Lebanon is probably sadly a no-go since I'm sure some folks in the production office have seen the original 'Bourdain in Beruit' show and understandably don't want to chance a route involving live artillery fire and evacuation by US Marines.