Good answer by Marshmallow. I remember wondering the same thing when G40 was new, but Krieghund* set me straight. Dizzkneeland is correct that you can still disable an air base and then attack the adjacent sea zone free from scrambled aircraft, but it must be on separate powers’ turns. Marshmallow said it perfectly, that the scramble decision is made at the beginning of the conduct combat phase, so the aircraft are scrambled before the base is bombed.
*(Krieghund is the official A&A answers guy, and one of the writers of the rule book)