And: Reiser 4 didn't get merged into the Linux source, did it?
Compared to what? Murdering the mother of your children and dumping her body in a shallow grave? Totally normal thing to do. But lets focus on the important issues like how highly unusual is was for the victim to try to escape from an obvious psychopath with her children before she was murdered.
If released, what are the chances that he would again have children with a foreign citizen from a country that doesn't respect US child custody laws, and that she would plan to leave the country?
I don't think he'd get married again. I don't think he'd have kids again. I don't think he'd get into a relationship with somebody from any of those countries (Russia, Japan, and very few others) again. Even if all of that happened, the relationship might not go sour, and if that too happened, most likely the woman would stay right here in the USA to enjoy life in the USA. After all that, it is still unlikely that he would murder, because he knows how it turned out last time and because everybody would suspect him.
Also, don't assume he is an obvious psychopath. History is filled with non-psychopaths who murdered. It's tempting to label him now, with hindsight, because it helps to deny one's own capacity for murder. I'm sure he didn't think himself capable of murder until right before he did it.