A good move, avoiding any chance of b7-b5. The alternatives also lead to an advantage.
1. d2d4  1... g8f6  2. c2c4  2... g7g6  3. b1c3  3... f8g7  4. e2e4  4... e8g8  5. f1e2  5... c7c5  6. d4d5  6... d7d6  7. h2h3  7... e7e6  8. g1f3  8... b8a6 [%c_effect a6;square;a6;type;Inaccuracy;persistent;true] This is too slow, and White gets a comfortable advantage. 9. e1g1  9... a6c7 