I work making investments in private companies. We manage this issue of knowing what executives make in the companies in which we invest just fine without the government's help.
You, being a much larger investor, have much more clout in getting that kind of information out of a private company. And if public companies were able not to disclose executive you would still have much more power than a small investor to find out that information if you want it.
I have no problem with all investors or potential investors in publically traded having access to that information.
I have no problem with investors insisting on access to this information either.
However, I as a private citizen have all the means I need of insisting on it and/or avoiding investing in companies that refuse to disclose executive salaries without the government's help.