One one hand, I think it's canny debating by yourself, as once the comparison is made the natural repugnance to the former stains the lattter with a ****-like substance thats hard to wash-off. However, are there really comedians telling jokes about child-porn? For me, that's totally out of order, but something that should be dealt with in isolation, unless you're saying that there is a general trend towards kiddie-porn jokes among comedians, which I would find, well, unbelievable, in the worst way.
It would be a mistake to legislate comedy, in fact I don't know how it could be done effectively. Comedy is just an amusing parody of life imagined, told by one person to another. What (other than child pornography) would you want to stop them from doing/saying?
How about gay jokes, are they OK?
What if some gay guys strenuously complain?
What about if it's in a pub, and you're telling me the funny gay joke, can you be arrested, as you're saying the joke in a public place?
How effective do you think legislation would be, given the viral nature of comedy?
I think it's a non-starter. It reminds me of 'Demolition Man', where people are fined for swearing, and they get a ticket, and Sly don't know how to use the 3 sea-shells, so he gets all the tickets and wipes his ass with them. If you see what I mean.