That was the purported reason for it. The LGBTQ2S+ people I know are terrified. Of being forced back into boxes, which become closets.
I know a bunch of terrified people too.
I met a lot of kids in my work. Many came from horrible or plain dysfunctional homes. The blind focus on parental rights opens up a lot of potential for various forms of abuse. I imagine most parents want to determine how they raise their children. That is different from the "parental rights" I'm seeing in the protesters. People I've met with those views often do not recognize children's rights. Children are a form of property and don't get their own rights until they leave home.
Then there's the whole "promoting" transgenderism. Are they even aware of how small a percentage of people fall under that group? People don't just whimsically transition to the other gender. Some may "try out" aspects of the other gender. They don't come out and go through the process of transitioning on a whim. It takes a lot of courage to come out. Most that I've met want to be "normal" in the worst way.