Considering what happens in the game, maybe it was safer for Black to play either 9...f5 or 9...Ng6, with a good position in both cases.
1. g1f3  1... d7d5  2. c2c4  2... d5d4  3. b2b4  3... g7g5 A bold move, that's for sure. 4. h2h3 A good and solid reply. 4... h7h6 The pawn must be defended sooner or later. 5. d2d3  5... f8g7  6. g2g3  6... e7e5  7. f1g2  7... g8e7 Black's plan is to castle and play f7-f5 - his position is very active. 8. b1d2  8... e8g8  9. d1b3 A new move.