She's a celebrity. Millions of people who will never meet her will nevertheless take an interest in her sex life; it's in the job description.
That's the real reason why celebs are always mouthing off about politics. It's not because they think their acting skills mean their political views must be correct -- anybody who has political views thinks something of the kind -- it's because they know that people will listen to them. If strangers will pay attention to your sex life, they will pay attention to your politics, just because they're yours.