Wow, what a twist.

I'd say that doesn't really apply though because not only is consensual BDSM invisible as a minority classification, it actively tries to remain hidden in public. It is inappropriate to display such things to people who haven't consented to being shown them. That's why you don't wear a gimp suit to go grocery shopping, the other patrons haven't consented to being part of that scene. So if anything someone who engages in BDSM would be very much offended see master/slave used casually in a public setting.