Thanks to Facebook's new privacy settings, it's not necessary that EVERYONE sees what she says. I have several "friends" lists set up on FB, which automatically filter out certain posts (Farmville people automatically don't see ANY of my posts, for instance). I have another called "Shh!" for people who I really only want to share certain things with, so when I make a post that I feel might offend them for whatever reason, I simply select to exclude them.
It's possible your cousin's husband has sensitive people set aside on a list that won't see posts like this. If YOU'RE uncomfortable with it, you can always bring it up to him that you'd maybe like to be left out of such, um, ruminations, but without being logged in to your relatives' FB accounts, you don't know for sure what they are or are not seeing.
Unless Nana is already adamantly voicing her approval, of course.