I mean nothing personal by it but all I see when I see posts like yours (and many others in this thread), is that the average person understands nothing about psychopathy.
What he did was premeditated. His brain is wired in such a way that killing his wife was always an option. No amount of neuroplasticity will override this baked-in reality of who this man is. Teaching psychopaths social skills will not provide them with the idealized "personal growth" you imagine.
I highly recommend, "The Psychopath Test" by Jon Ronson (of "The Mean That Stare at Goats" fame) as an amusing but on-point introduction.
It's not even the murder so much as it's the premeditation. Even the most non-psychopathic mentally ill individuals with the most awful intrusive thoughts will still have an active conscience telling them not to do the things their minds are telling them to do. This is a big part of the torture schizophrenics are going through. Psychopaths do not have a conscience and psychopathy is not a diagnosis. The diagnosis given to psychopaths is typically Antisocial Personality Disorder, of which I have no idea if Reiser personally qualifies. But yes, premeditated murder is going to rank quite high in the scoring criteria. Hans believes/believed that he had the right to kill his wife. Even if he legitimately feels sorry (and I would be highly skeptical), the question becomes whether he actually feels sorry for the murder or the fact that it has landed him in prison (and that he only really feels sorry for himself).
What's your evidence that the murder was premeditated though? As far as we know he didn't even look into how to cover it up until afterwards.
All the known facts are congurent with someone who acted in the heat of the moment and then tried to get the best result for himself considering the very bad situation he got himself in. Trying to cover up the act and mislead the court is certainly not very ethical but it is a far cry from the murder itself being premeditated.