*Man blindfolds a woman and ties her up as part of consensual bondage.
Woman then has sex, thinking it is the same man. Unknown to her, another man has entered the room and it is him she is having sex with.
No one would argue against that being called rape. I fail to see how, in the GN case, the factual matrix is significantly different. Just substitute a dildo for the second man's penis and what you have is identical.*
Really?? If my DH and I were to have consensual sex involving bondage, and he used a dildo on me without telling me, then I probably wouldn't care very much. If he sneaked his best mate in to take part, without telling me, I would be horrified!!!
To me the GN case is far closer to the first than the second in terms of what actually happened. (Although of course I don't mean that the victim in this case shouldn't care. Clearly there has been a deliberate and sustained deception here)