In at least Arthur, Diana and Wally's cases, death was a very strong possibility.
Arthur, Diana, Wally, and J'onn - and, at the time, he had no way of knowing that what he did to Plas wouldn't kill him - although I will grant that it's possible that the smashing him part was a flourish added by Ra's.
A rundown of what was done, for those unfamiliar:
J'onn: Nanites insinuating themselves with his skin, which burst into flame upon contact with oxygen. Arthur: Hypnotically induced hydrophobia. Diana: Put into an illusion of endless combat. (According to Ra's, potentially lethal for her.) Plas: Frozen, then shattered into a million pieces. Wally: Induced a superspeed grand mal. Clark: Red K (created to be less lethal, but untested, so the actual results - making Superman's skin transparent, so he absorbed too much solar radiation to control his powers properly - weren't known.)
Then there's Kyle, who's hypnotically induced blindness seems absolutely harmless in comparison. Rendered him powerless, and was no doubt unpleasant for him, but lacked the level of stress and pain the others involved, even ignoring the potential lethality.
It's actually funny that the four who were subject to the worst are actually split 50/50 on the vote. (J'onn's refusal to condemn him makes sense, since it would be hypocritical...Wally's is more surprising.)