The cruelty and unusual is the point
By 
Another gratuitous torture-killing ordered by 5 Supreme Court Republicans:
Alabama, meanwhile, passed a law that nominally allows people on death row to choose a method of execution other than lethal injection, but only if they act within a very short window of time. As Justice Elena Kagan describes this Alabama law in her dissenting opinion in Hamm, “a recently enacted state law gave those inmates one month to select execution by nitrogen hypoxia” — where the inmate is placed in a gas chamber filled with nitrogen gas and asphyxiated — “rather than lethal injection.”
Many experts believe that nitrogen hypoxia is much less painful than lethal injection, especially if the state does not have access to reliable anesthetics. Although, for obvious reasons, it’s impossible to conduct an ethical experiment on actual people to determine if one method of killing is less painful than others.
The specific legal issue in Hamm concerns the paper form that the state gave inmates, which allowed them to choose nitrogen hypoxia over lethal injection. As Kagan notes, “the form was written in legalese, and according to unrebutted evidence, an inmate needed at least an 11th-grade reading level to understand it.” But Reeves had “cognitive limitations.” He had “the same reading ability as an elementary-school child,” and “one expert testified that Reeves’s ‘reading comprehension was at the 1st grade level.’”
A lower court determined that, under the Americans With Disabilities Act, the state needed to help Reeves understand the form before he could be executed. But five justices, in a two-sentence order that offers no explanation whatsoever of why they reached this decision, permitted Alabama to move forward with the execution — and to do so using lethal injection.
The question wasn’t even whether Alabama would get its execution; had the Court just allowed the lower courts to resolve the issue and comply with the ADA the state would just probably have had to use a method less likely to result in excruciating pain. But this is definitely the Gorsuch Court now.