"He's not feeding, he's just bad"

You mean inting right? Because feeding simply means dying over and over (According to boards, the Yasuo on your team, but never the one on the opposing team). What you are describing is people that are purposely dying, which is labelled as 'int feeding'. Feeding=/=inting (in most cases).

It's still a really hard thing to prove. It's when they have a history of it or they verbalize their intent to feed is when it becomes intentional punishable. Edited.

No no no, i'm a retard on the boards/a rioter and i can tell you that was just a bad game™ no intentionality whatsoever in his actions, if you disagree with me you're a toxic racist bitter noob that would have otherwise won if you were just better at the game.