I was in a TF2 game last night and several people were talking about catbots and I had no idea what they were talking about. In the PCGamesN article[0] it mentions "cathook"; maybe they are related. Either way, I guess I can't play TF2 anymore. At least until Valve figures out what to do about this.
This is such a popcorn-heavy story. I can recommend Reddit (for example [0]) for juicy details. Code was leaked by a Valve employee. Also there are enormous chatlogs with that guy who spills the beans on all kinds of stuff.