My 2 cents....I'd punish.
ASSUMING that the pregame chat was littered with problems created by his teammates, his initial outburst was "understandable". Not acceptable, but we're assuming the worst.
After that, he/she was given opportunities to reconcile and help from his teammates. His/her speech continued to be only negative, and in instances where a positive comment could have been made, there was silence. Until, of course, an opportunity to be snarky arose, then it was gloves off.
Additionally, claims of "I wasn't AFK, I was in the jungle" are, I believe, grossly overstated. One would believe that a CS count should be greater than 27 at the 33 minute mark, assuming that one was "in the jungle instead of ganking". One full clear of the jungle is 15 CS. That means that in 33 minutes he/she was not able to even complete two full clears of his/her own jungle.
My best guess, even ignoring his/her comments, is that they went AFK, just based on CS and K/D/A stats, but mostly the CS. Even the support had more.