Kilobear, I don’t think anybody was trying to legitimize it. They have a nisayon that the rest of us can’t comprehend. Whereas straight people have permissible ways to indulge their tayvos (pas bsalo), the others do not. This causes them trmendous pain. They were only asking for some sympathy which they deserve. WHo knows if they are on a much higher madreiga because they get schar for resisting things that the rest of us have no desire for. Do you think we get schar for this mitzvah? We don’t even get one ounce, since it doesn’t take any effort. The same I believe with eating rats or snakes. Most of us do not get schar for that since it grosses us out anyway, and we would never think of doing it. One can only get schar for a nisayon.
As far as it being an illness, so if we grant you that point, then al achas kama vkama you must give them sympathy. One who is sick and can’t control what he says, or a manic depressive who loses touch with reality and acts irrational certainly deserves sympathy, not anger, even if he does something outrageous like somersaults in shul.