It stops being natural selection then. Of course we've been screwing up natural selection for a long time. The first time a doctor kept a kid from dieing from some disease and that kid went on to have kids we broke natural selection.
I agree, at least from an evolutionary perspective.
What then is "health"? Is it "the proper operation of the body," as the dictionary defines it? But what is "proper operation" when the human body is in a perpetual state of transformation? Why do some scientists work to restore "proper operation" of the body, while others deny that such a thing exists?
Additionally, why is the act of preventing a child from dying of disease a rupture of the rubric of natural selection? Hasn't the human brain evolved to promote our survival, as in this example? So why not continue to "evolve" our brains "forward" as the transhumanists seek to do? Aren't they working for our survival as a species?