I think because he's part of the human condition.
We have geniuses such as Einstein and Musk, and heros such as the guy who stopped the Huntingdon train stabber, sorry just first examples that came to my mind. They're examples of how great humans can be. They're outliers in a positive sense. Developmentally speaking, every brain evolves differently- we take the good. On the other hand, there will be unfortunate people such as JB who develop brains that lead them to actions such as his. Basically, his brain is fucked. He's got the totally shitty end of the evolutionary stick. So, I think yes he should be accommodated. He's a part of the human race. And by accommodated I mean locked away forever. I dont think we can just kill him. He disgusts and scares me, but he's part of us.
Just my opinion- I'm not explaining very well.