I think the line for me would probably be between reality and fictional circumstances. In this circumstance, a real person actually took their life, which (at least to me) is not really a joking matter. On the other hand, if there were some joke about a fictional character involving suicide, I probably would not be (greatly) disturbed. I understand that not everybody would have this reaction, but I have known people who tried to commit suicide so it is a bit different for me I guess.