Suicide related materials actually makes some sense, depending on how extreme the censorship is. There's research (I don't have the reference handy, but it's described in Cialdini's "Influence") that estimates that in the US, each well published suicide results in an additional 48 deaths through suicides and murder-suicides, as people who are suicidal at the time appears to be more likely to go through with it in those conditions.

So if you are to censor something, suicide descriptions would be far more morally defensible to censor than porn, as to my knowledge there's little to no evidence that increased access to porn leads to increases in harm to other people.