It's ironic that I feel similarly discouraged by the accuracy statistic, but because I think the Tribunal is too lenient.
See, this is a difference of opinion. To me, this is a clear punish. Just taking a look at game 1:
He starts off already being negative to the duo queuers. "I'm already Plat, I don't care lol" is also negative attitude. He follows this up with verbal abuse "you suck", "shut up scrub". Overall, it feels as if he was intensely negative to his teammates and constantly blaming them instead of providing constructive feedback.
Games 2 and 3 are similar.