Put yourself in my shoes. If you believed it was killing, would you just shrug and go, "eh"? No. We as a society don't let people get away with murder.
Not everything is equally weighted. Just because I think some things are wrong doesn't mean I'm going to go trample over people's right to do them. Nothing about LGBTQ+ sexual practices harms anyone and we as a society have no good reason to put a stop to it. I'd argue we have a civil duty to protect it. That, to us, is the difference.