Why would someone do this?

I had a salty Jinx afk after intentionally giving first blood because their support accidentally picked Warwick. Unfortunately they walked in circles for the entire duration of their afking, so they weren't automatically put as afk. I told the enemy team to report them for afk and they said "no im not afk im fingering my ass to 9/11 recounts" they had 3 lines of chat like this throughout their afk. Eventually they bought an archangels staff and fed two kills before we surrendered. The worst part is since they finished with only 3 deaths they won't be flagged as a feeder and won't be for afk cuz they walked around. I'm fairly certain the report system won't do anything about this.