Is this griefing?

So just finished a game with a "griefer". Already in the champ select he banned one of my teammates intended champ and when he picked ziggs as support I already had a bad feeling about this game. Didn't wanted to dodge, so I just went through with it. He stole ADCs farm all game, didn't support him at all, went around the map farming jungle and even stealing farm from me (middle), ulting a 20ish minion wave with ziggs ult. Any normal person understands that he was trolling, he even admitted that it is fun and he was enjoying it. But what is actually considered griefing and trolling? I bet that Riots automated system won't catch any suspicious activity and only a person manually reviewing it would see him griefing. Or maybe stealing ADCs farm as support, taking jungle farm and ulting big minion waves by ziggs support isn't considered as trolling? I don't care if its a normal game or ranked, he just ruined the game for other 4 people. I felt really bad for my adc, cuz he was decent, but skill doesn't really matter when you don't have items and no support. I should probably be more scared about getting banned because I called him an idiot instead of him griefing all match I think. What do you think? Is this griefing or just playing in a non-meta way as others call it and say that it is acceptable. I actually wouldn't mind if he got banned, but he won't 99%. So I feel pretty bad that he was intentionally ruining game for me and other teammates.
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