I don't want some ******* to be able to vote my rights away because they have a problem with me and that I "offend" their religious beliefs. America was deliberately and intentionally set up to not be a democracy in order to preserve rights and protect people from the whims of the majority. Afterall, to the Founders democracy was a term that is synonymous with mob rule.
And they don't legislate anything. That is the job of Congress. The Supreme Court hears cases where the nature of them call into question the Constitutional legalities of an issue, and make their judgements based on interpreting the Constitution and prior precedence. Such as, when the Supreme Court inevitably hears cases of transsexual discrimination and bathroom use, they will consider things such as Title IX, the Equal Protections clause, prior Federal Circuit Appeals cases, and the Civil Rights Act, and will most likely rule North Carolina's law unconstitutional. It's not an act of legislation, but rather declaring that a certain law causes undue discrimination and is thus a violation of the Constitution and not legal.