AlpArslan got banned but he won about 99% of his games except by giving up probably to keep his score down(bot?).
But this game he lost and it looks so complicated, I can't figure out for sure what the losing move is. I think move 12 or 17 are candidates.
http://en.lichess.org/DaA7WwPY#22Wasn't 19...a5 an easy win? 20. Bxb7 d5 21. Bxd5 a4 22. Bb3 axb3 23. cxb3 0-1
I think you're right, but it's too easy for a bot to miss, maybe that game was just bot assisted.
The losing move was 24... d1=R
Promoting to either a king, bishop, or queen wins on the next move as the c and e pawns are both defended and just grab whichever is still defended. Not sure who wins if promote to knight, but promoting to rook is an awful move.
As for being banned... I don't think computers are capable of being used to play anti chess. I could be wrong though. Also the time allowed for this game is 2/0 so a person with only 2 minutes of clock is not likely to be using an engine to assist in a game that short.
How do you know this player was banned? I only see "account closed". That doesn't mean it was a banning although it might.
It's surely somehow possible to write a program that directly connects an antichess engine to the GUI.
Why shouldn't computers be able to play anti chess? They easily beat any human.