By 'healthy', I did mean evolutionarily successful. However, I wouldn't go to great lengths to defend the statement, so I think you did catch me saying something I didn't entirely mean.

Someone can be intellectual and emotionally detached at times, and this can help someone make more rational choices. However, if someone is too emotionally detached they don't empathize with other people (or even themselves) and don't care about their goals. So I meant something more general like apathy than lack of empathy. So my claim is that biological stop-guards prevent us from being too apathetic about external reality. (For example, when I imagine wireheading, I start empathizing with all the people I'm abandoning. In general, a person should feel the tug of all their unmet values and goals.)