Hey there! I'm coming back from my otherwise mute lurking to dispel something here. Antisocial personality disorder does not mean you don't feel anything for others(ie lack empathy). That's sociopathy(which is a rare subset of APD). APD, that I have, means you have a difficult time communicating and/or understanding feelings(it's a broad diagnosis that covers many actual behaviors). In my personal case, I have a difficult time expressing my own emotions to others for a lack of ability to communicate them in a way that my listener understands(as opposed to a lack of understanding of my own feelings myself which can also be APD).
Sociopathy, that a friend of mine has, is primarily identified by a lack of empathy and an inability to show legitimate feelings towards others(as well as manipulation to conceal that behavior). This also is very specific in that it doesn't mean you don't have emotions, but rather your emotional spectrum is narrow. For my friend, he does an excellent job of being a decent human being, and as a rarity does not lie to others that his behavior is an act(he explained to me that he knows how he is is wrong, and so he's trying his best to make up for it while being honest; most sociopaths aren't like this).
Sensei however likely does have APD but not sociopathy, because his contradictory internal monologues seem to alude to other feelings but his response to himself seem to be to immediately bury those feelings. That's reminisce of a conditioned response, and people with such behavior usually lack emotional intelligence. They don't understand their own feelings, and how they react to them can be widely different from person to person. In my own case, when I was younger, APD for me meant I also did not understand myself. Years of therapy, research, and trying to grow up later, I'm able to at least understand myself.
So the thing I should clarify here and the reason I wrote this wall of text was in defense of that man you met. While sociopathy is a form of APD, it is usually not what most diagnosis mean. And while I cannot speak for him spefically(because maybe he does have sociopathy), I don't want others to make a wrong assumption and believe that all persons with APD don't feel empathy towards others. We do, and in fact, often more strongly than the average person which is contributory to our difficulties with handling them.
And since I know I have difficulty with communicating my own emotions, I'm going to robotically state that the above was meant to only be educational and clarifying, not confrontational(your statement wasn't wrong, but its lack of context would easily create misleading perceptions). So I hope I didn't come off as offensive or rude. :S