Just Played With a Long-Time Botter

Who, unsurprisingly, isn't banned.

The guy said nothing during champ select and locked in Jungle Graves after we had a locked Jungle Ivern. Game loads and he has masteries that no Graves would use. Proceeds to go down mid without saying a word, clearly running some sort of bot. He didn't run straight to mid, he ran down mid, stopped, kept running, stopped, etc. He was dead within 2 minutes after standing toe-to-toe with Twisted Fate and not moving. He respawns and makes the same erratic movements, this time towards top, where he dies again. Repeat with bottom lane, repeat the remainder of the game. At times he would freeze as the enemy was approaching, then still run straight into the crowd without firing a single shot. He ended 0/14/0 without ever saying a word. I'm not sure if I actually saw him cast a single spell.

Looking through his match history, this has been constant. He has a game with Jinx going 0/10+/0 with Smite. He has games with 1 kill and many deaths running Smite on champions that don't jungle, without setting masteries. He tends to play Twisted Treeline, probably because of how poor his bot is in Summoner's Rift (although he does terribly in TT too).

If Riot takes these things seriously, how come anyone with access to LoLNexus can figure out someone's botting, but you don't ban them? I wonder how many Xerath scripters are just laughing somewhere where their new ranks and no bans.