I'm on the fence, but at this time, I am thinking that this was a terrible accident. Make no mistake, I'm not defending JRH – this guy is a terrible parent, husband and employee – but I'm not sure he's a cold-blooded child murderer. I know I am a member of a tiny minority here, so please don't skewer me!
There are several reasons why I think Cooper's tragic death wasn't planned, but the main reason is, ironically, JRH's disgusting behavior. Just about everyone now knows that after a suspicious death, phone, text and internet records will be analyzed. That's even more true for someone working in a tech field like web development. So I have a lot of trouble believing that if he planned this, he would send lewd photos of his anatomy and text with multiple women all day while his child was dying. He may not be a genius, but he would surely know that his phone and internet records would be scrutinized.
Perhaps, after eating at CFA, his mind immediately turned toward his titillating virtual activities, and all thoughts of his child vanished. I would be curious to see if he sent or received texts or chat messages before he arrived at work. Perhaps he and his wife were so afraid he would leave Cooper in the car because he had a history of being absent-minded, or maybe because it had happened before. Parents DO sometimes forget when an infant is in the car - it happens quite often, and there have been several stories recently in the news. I don't have children, but I do really, really stupid things all the time when I'm distracted, and if I had a child this would be a major fear for me.
There has been no evidence so far, other than a brief visit to a "Child-Free" website, that JRH didn't love his child or enjoy being a father. His friends say he talked about Cooper all the time and enjoyed spending time with him. Sexting with other women and underage girls may be sick, but it is not solid proof he wanted to kill his child. Shocking as it may be, sexting and chatting on these kinds of forums and social apps is very common, even among married people. Ditto for marital problems or insurance policies.
I wish I could feel as convinced as some of you of his guilt - but until I hear more evidence, I am hanging out on this lonely fence.