How do people think this kind of behavior is appropriate?

I just played a game with an Udyr who didn't play very well, and ended up trolling his team because of his poor performance. I was Annie, and at one point in the game, Udyr tried to 1v2 a fed Trundle and Varus near Gromp, which ended poorly for him. I pinged I was on the way, but I couldn't get to him fast enough, and so he started to rage at me. Lissandra stepped in to explain that I couldn't have gotten over the wall fast enough, but Udyr wouldn't listen, and devolved into this album of his trolling.

He seemed convinced that being reported would do nothing, despite threatening to report me earlier in the game for "trolling", his view of me not being able to save him as I mentioned earlier. I hope he's just an edge case, as I know the report system has improved, especially with the automatic feedback the system provides, but it's surprising that people think it's OK to act and talk like that in-game.