What do they expect from him? He was but an ordinary virtual gamer who is no longer sure of what he currently is.
The former Sango was a cheerful kind of being who was accommodating and can be very emotional when the time calls for it.
This current Sango however holds no traces of the Sango from the past, from his life back on earth.
The way Zita looked at him when he walked out on her was as if she was looking at a cruel, heartless being.
But she is missing the point of it all. The fact that he is emotionless does not define his overall characteristics as a cruel person.
It only seeks to differentiate him from those who think or act solely based on their emotions or their desires.
That is the difference between he and them. One has the desire to grow stronger and because of that, he resorts to whatever means that will help them achieve their goal.