Sure, that might happen. But you're invoking a potential problem that might happen, when we have problems (gender and racial pay gaps) that are A. more severe than the potential problem you're invoking, B. already demonstrably occurring, and C. potentially correctable via salary transparency. If we can make a step towards correcting existing problems, and the best argument against it is "this might create a less-severe problem at some point in the future", we should probably take that step.