A newspaper not publishing political cartoons is not a free speech issue. If the government were banning political cartoons, then it would be. A newspaper can print or not print whatever it wants.
It may not be an issue of Free Speech (however you define it), but it's still an issue of freedom to speak.
(My point is that you're trying to dismiss an issue by claiming to not fit an arbitrary category, but you haven't argued why not being into that category makes it a non-issue.)
But self-censorship of the press can surely be an issue, no?
A cartoon can only transport so much, but it might give a hint about the bigger picture. Which I think is not taken into account with assertions like yours.
