First, thank you for much better edge cases than the usual "fire in a crowded theater!" and "slander!". Yours are much more interesting to talk about.
The nuclear example is the easiest to dispose of, since it involves an actual property crime (essentially trespassing).
The others are trickier, but I think the distinction in question isn't about what they did or didn't say, but rather that they aided and abetted an actual property crime. For example, we prosecute the driver of the get-away car just as much as we prosecute the people who actually rob the bank at gun point. This isn't because driving people around is illegal or requires close scrutiny, but because they were knowingly a party to an actual property crime.
Or, for a similar example involving speech, imagine that I pull a gun on you in a darkened alley and say "Your money or your life." Obviously a crime, right? Now add that we happen to be actors in a movie and I am reading from a script when I do so. Obviously not a crime. That is to say, it's not the speech that makes such a thing a crime, it's the actual property crime behind it that does so.
From that perspective, we can see that slander and libel should not properly be considered crimes, since there is no property crime to back them up (you can't have a property right in your reputation, since that exists solely in the minds of others). It's the same with calling Mohammed a pedophile, telling the king of Thailand to piss off, or simply transmitting information to the public at large about how to build a bomb from household ingredients.