@LM OhNoMyPants yes, I knew about that incident on ICC. But in that case, if I remember well, there was no opening system involved, the king went to e2, f3, sometimes g3 and then hyding on h2 (after an previous h3 pawn move) or something like that.
In the case of ...f6 and ...Kf7 I think that it is an opening system, horrible of course, but I don't think white is winning by force after those two moves. Actually, in a match between a strong GM playing white vs Stockfish playing f6 and Kf7, I think I would bet for Stockfish winning the match. Not sure in case of "Fischer's" opening ;-)
In the case of ...f6 and ...Kf7 I think that it is an opening system, horrible of course, but I don't think white is winning by force after those two moves. Actually, in a match between a strong GM playing white vs Stockfish playing f6 and Kf7, I think I would bet for Stockfish winning the match. Not sure in case of "Fischer's" opening ;-)