I know people that are very emotional, and can get overwhelmed by seeing others suffer -- but people that are absolutely "normal". I wouldn't call it "average" (for adults anyway) however.
I do think he's wrong about not having had a limited form of empathy: literally feeling other peoples pain is empathy. That doesn't mean he didn't care, or loved before - but it absolutely sounds like he had trouble: "understanding and entering into another's feelings" (from WordNet, my emphasis).
It's a fascinating story, like a real-life "The Speed of Dark", by Elizabeth Moon (in part inspired by her son):
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