What part of that article supports your point? The only thing I see there is that he made up multiple different stories to try to explain her absence.

That he claims that he killed her to protect his children. You don't make up a reason like that on the spur of the moment while involved in a crime of passion.

"His defense essentially was that he killed his wife to protect his children from her."

That he made up different stories at different times is besides the point, the point is: you can't believe a word he says either way so any defense of a crime of passion is just as baseless as this one, though this one is actually much more believable and fits the evidence available. All of it points to a very smart guy who killed his wife because he thought he could get away with it but failed at that (and not for lack of trying) and who now thinks he can present himself as 'a changed man' when really he isn't.