Example: I am a lawyer (in training). Someone contacts me and wants me to defend their rights on a particular issue. I do not agree with their position on that right. Do I still have to defend them? No. If I think their claim is frivolous and that they will waste more money defending that right than finding a simpler solution, I have the discretion to refuse to defend that person. That does not mean the right will not get defended; I'm sure someone else will take the case because the dollar signs will attract him/her.
In the case of these cartoons, freedom of speech/freedom of the press may dictate that they have a right to be printed, but that did not take away the papers' discretion not to print them. They simply chose not to exercise that discretion.
Rights go hand in hand with responsibilities. Never forget that.