I don't care what he wants; if he prefers death to life in prison, that's great- for once we can agree on something. His opinion on the matter is irrelevent once convicted. If he's dead, he can't preach, he can't write books to poison Berkeley students' brains, he can't recruit more people to the cause, he can't communicate with like-minded individuals or conspire with them to carry out more acts of terrorism like the 1993 WTC bomb plotter did with his lawyer Lynne Stewart, he can't give interviews to an adoring and breathless press, he can't raise a "Free Moussaoui" fan club, he can't stab a prison guard in the eye like that other terrorist did, and he can't ever get out due to some silly-arse supreme court decision in 2022. Besides, his execution would free up air and space for some endangered species and perhaps even provide fertilizer for a few daisies.
Why expect Americans waste their lives as prison guards for human debitage when they can be employed elsewhere in much more fufilling and productive ways?