Although the circularity of the logic of insanity as demonstrated by the very fact that a man desires to be eaten (because he is insane, because he wants to be eaten, because he is insane…) loses credibility due to the redundancy of such thinking, the implicit conclusion that the author comes to regarding this matter, "if every person with emotional problems were denied the right to determine what is in his own interest, none of us would be self-determining in the eyes of the law, except those of us who had no emotions to have problems with," may very well be inductive. It certainly seems to be a considerable assumption to say that people with mental (or "emotional") problems, should not be restrained from their actions, because in doing so virtually everyone -- who is at least half-crazy, if not further along on his or her way to being crazy -- would then have to be restrained. It certainly seems inductive to try to convince readers that by restraining people with these tendencies from doing what they want, there would be no self-determination because everyone is crazy in some shape or another.
This story about Meiwes and Brandes is certainly repulsive to virtually any civilized person. Does Dalrymple have a case that it should be permissible because both adults were consenting? Unfortunately, not. There are still laws, and in very rare cases is it legally permitted to kill another. Euthanasia has very strict laws, and ramifications if those laws are transgressed. Although it may have been morally right for these two men to engage in cannibalism, legally, neither morals nor consent gave these men the right to do what they did.