Uhhh... well, you wrote: "I would still consider having sex with a blacked out person as rape, even if that person consents later." Not sure where we're talking past each other here, but this seems to go against the idea that implicit consent can be given. Did you mean having sex with them without implicit consent?
Well no, the example I was referring to was spanking a person without asking first, which Sommerswerd had mentioned, to which you had written: "I would still say, however, that specifically in your BDSM example there
was some sort of consent that wasn't outspoken, something much more nuanced like body language, voice and intonation, mimic."
That act of slapping is done before the person can withdraw consent, just as sex-while-passed-out is done before they can withdraw consent. The "lived experience" is even worse if you're being slapped, because you are conscious while it happens.
So... no, I don't see much of a difference, other than the magnitude. People who don't like being spanked are more likely to be able to just brush it off, that's likely not as easy when you wake up, realize a person who you had sex with before has now also used you again while you were asleep. But still, just spanking a person can go horribly wrong, especially if the person who's being spanked has lived through actual abuse (that the person doing the spanking may not know of) and gets sent into traumatic memories by it.
So I really cannot see how you can argue for implicit consent in one case, but in the other case deny the possibility of implicit consent and say a rape has taken place even if the person acted on implicit consent and the other person then later likes that it has happened.
Because here again:
How is that not also true for spanking a person without asking first purely based on how you perceive their behavior, and hoping for the best?
I can see arguments for and against both positions, but arguing for one and against the other at the same time seems inconsistent. But maybe this too is part of the misunderstanding of the other post, so feel free to tell me where I got you wrong there.
Regret and post-act withdrawal of consent are not the same though. People who argue for post-act withdrawal of consent usually mean that they want to retroactively change the status of consent of the time that it happened, not that you now feel differently about it.
Here's an example:
I really suggest reading that article, because it does give quite a bit of insight in why people think that's acceptable, but the main point is that post-act withdrawal of consent literally means changing the status of the act that happened in the past, that how you
feel about an act in the future changes what the act was in the past - not that you've changed your mind about whether it was a good idea or not.