This is a good point. I do have one thought about the specific topic under consideration, though. Culturally, there's a general inability to talk rationally and sensibly about many sexual topics. Given the importance of sex to human life and human happiness, this seems like a serious problem, and many members of the less wrong community have shown an interest in trying to do something about it. Since the inability to discuss pedophilia rationally seems to be connected to this general difficulty in discussing sexual topics rationally, it seems to be a less than perfect match to the "yellow" example. Strategic questions seem to be relevant; is the general cause of talking more rationally about sex helped or hindered by bringing up the extreme cases? I admit that I find it somewhat plausible that the answer is the latter, that it is more productive to focus on less extreme examples, but plausible is different from definitely true. Thus, there might be some value in trying to investigate the strategic questions, while in the hypothetical "yellow" example there seem to be fewer strategic questions worth asking.