Well, even atheists set limits to what they can do in sex.
I set my own personal limits for all activities. I won't do ass to mouth penis routines - but I'm fine if you want to.
Also - I don't drink alcohol.
That is a sign that they don't really believe in total liberties...
I don't believe in total liberties - I've not met any atheist who does.
But I do believe you should be free to do as you will so long as more important rights are not impinged on.