The culture war came later, when liberals tried to use trans people to promote their own view—which you aptly characterized above—that people should be allowed to express themselves free from traditional social norms and roles. Liberals rushed to promote things like drag shows, which have nothing to do with trans people, and everything to do with voluntary self expression. As RuPaul (a cis man) put it: “Drag says 'I'm a shapeshifter, I do whatever the hell I want at any given time.’” That liberalism is what has “conservative parents riled up for a culture war,” when they mostly didn’t bat an eye at actual advances in trans rights.