We can have a solid, productive argument about the way that they death penalty is applied, and how it’s more likely to be used in racist and classist ways. (My stance is that some people need to be completely removed from the possibility of being returned to society; the overwhelming majority of the people that fall into that extreme risk category are white, and almost always have famous pseudonyms, like Co-Ed Killer, Night Stalker, Zodiac, Green River Killer, Father John Geoghan, and so on.)
You can’t argue in good faith that nitrogen is anything other than a very soft way to die.