People are going to need to die in controlled ways; whether in believing some people should be murdered by the State, or in believing people should be allowed to end their own lives, there are few Americans who don’t fall somewhere outside of the set of people who think there is never a case for controlled human death. Most of those people are probably Amish, or some branch thereof.
Alabama clearly fucked this one up - I guess that’s what happens when you drive all of the STEM folks out of your state. There was no reason - other than wanting a person to suffer, as you said - for it to have gone so wrong. Justified or not, if I were to ever find myself in that chair, asphixiation by nitrous nitrogen is absolutely the way I’d want to go. And that’s the most basic measure of humanity we need: do unto others.