It's more of this mental aspect that fucks with my head. There's the whole issue of consent with a tied up zombie. I mean, they are dead, all they want to do is eat brains, out of no real malice, but out of programming. It's not exactly the same as a fucking a sex doll, because it's still a human body that had a lived experience and deserves a bit of respect. And if they were a shitty person when they were alive, that would just make me want to kill the zombie, as opposed to rape it.
I'm not even put off by the physical aspect of fucking a zombie. Imagine fucking a Stacy with zombie makeup on. It's still Stacy.
What if too, they were a hot sex zombie, that's still alive looking like in the movie Shivers, where they WANT to get nasty, but again, out of programming. They are practically zombie rapists anyway, so I guess it wouldn't matter.