Exploited I don't think that framing your argument around substantive freedom works. Someone spending a year in jail for not making a cake seems to be a much larger infringement on substantive freedom than the inability for gays to purchase a cake at a specific bakery.
It seems reasonable that states can mandate behavior of businesses and citizens to shape society. Whether it is through drug prohibition, anti-nudity laws, anti-discrimination, state religion ect. The question is to what degree do we allow the state to do this?