Catalysis of the reaction: 1D-1-guanidino-3-amino-1,3-dideoxy-scyllo-inositol + pyruvate = 1D-1-guanidino-1-deoxy-3-dehydro-scyllo-inositol + L-alanine.
L-alanine-N-amidino-3-(or 5-)keto-scyllo-inosamine transaminase activity